assignment 15 query

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course MTH 151

11/20/14 around 11

If your solution to stated problem does not match the given solution, you should self-critique per instructions at

http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/levl1_22/levl2_81/file3_259.htm

Your solution, attempt at solution. If you are unable to attempt a solution, give a phrase-by-phrase interpretation

of the problem along with a statement of what you do or do not understand about it. This response should be given,

based on the work you did in completing the assignment, before you look at the given solution.

015. `query 15

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Question: `qQuery 3.4.6 write converse, inverse, contrapositive of ' milk contains calcium'

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Your solution:

convers - if it contains calcium, then it is milk

inverse - if it is not milk, then it does not contain calcium

contrapositive - if it doesnt contain calcium, then its not milk

confidence rating #$&*: 3

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Given Solution:

`a** 'Milk contains calcium' can be put into p -> q form as 'if it's milk then it contains calcium'.

The converse of p -> q is q -> p, which would be 'if it contains calcium then it's milk'

The inverse of p -> q is ~p -> ~q, which would be 'if it's not milk then it doesn't contain calcium'.

The contrapositive of p -> q is ~q -> ~p, which would be 'if it doesn't contain calcium then it's not milk'.

Note how the original statement and the contrapositive say the same thing, and how the inverse and the converse say

the same thing.

NOTE ON ANOTHER STATEMENT: If the statement is 'if it

ain't broke don't fix it:

Converse: If you don't fix it, then it ain't broke

Inverse: If it's broke, then fix it.

Contrapositive: If you fix it, then it's broke. **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question: `qQuery 3.4.18 state the contrapositive of 'if the square of the natural number is even, then the natural

number is even.' Using examples decide whether both are truth or false.

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Your solution:

if the natural number is not even, then the square of the natural number is not even

both statements are true

2^2=4,10^2=100,8^2=64,126^2=15876, ect we can assume that the first statement is true

3^2=9,5^2=25,25^2=625,ect we can assume that the contrapositive is also true

confidence rating #$&*: 3

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Given Solution:

`a** The statement is of the form p -> q with p = 'square of nat number is even' and q = 'nat number is even'.

The contrapositive of p -> q is ~q -> ~p, which in this case would read 'if a natural number isn't even then its

square isn't even'.

STUDENT RESPONSE WITH SOMEWHAT PICKY BUT IMPORTANT INSTRUCTOR CORRECTION: if the natural number isn't even , then

the square of a natural numbewr isn't even

Good. More precisely: if the natural number isn't even , then the square of THAT natural number isn't even. To

say that the square of a natural number isn't even doesn't necessarily refer to the given uneven natural number.

COMMON ERROR WITH INSTRUCTOR COMMENT: The natural number is not even, if the square of a natural number is not

even. ex.-3^2=9,5^2=25 This statement is true.

** You have stated the inverse ~p -> ~q. It doesn't matter that the 'if' is in the second half of your sentence,

the 'if' in your statement still goes with ~p when it should go with ~q. COMMON ERROR WITH INSTRUCTOR COMMENT: If

the natural number is not even, then the square of the natural number is not even.

This statement does not involve square roots. It addresses only squares. And 26 isn't the square of a natural

number. **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question: `qExplain how you used examples to determine whether both statements are true or both false.

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Your solution:

for the first statement that says if the square of a natural number is even, then the natural number is even i

simply took the square of different random even numbers such as the square of 4 is 2 and the square of 25 is 5 and

even the square of 15876 is 126. we can never test ever square of every even number but we can make a good guess

that the statement is true after seeing many examples

the contrapositive of this statement says that if the natural number is not even, then its square is not even. we

can test this for truth by finding the square of some odd numbers such as the square of 9 is 3, the square of 25 is

5, and the square of 625 is 25. these are just a few examples that can lead us to believe that this statement is

also true

confidence rating #$&*: 3

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Given Solution:

`a** The first statement said that if the square of a natural number is even then the natural number is even. For

example, 36 is the square of 6, 144 is the square of 12, 256 is the square of 16. These examples make us tend to

believe that the statement is true.

The contrapositive says that if the natural number is even then its square isn't even. For example, the square of

the odd number 7 is 49, which is not an even number. The square of the odd number 13 is 169, which is not an even

number. This and similar examples will convince us that this statement is true. **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question: `qExplain why either both statements must be true, or both must be false.

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Your solution:

the truth tables for the conditional statement and the contrapositive are equivalent which means when 1 is true then

the other is also and if one is false then the other must be false also

p q p->q ~q->~p

t t t t

t f f f

f t t t

f f t t

confidence rating #$&*: 3

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Given Solution:

`a** The reason is that the truth tables for the statement and its contrapositive are identical, so if one is true

the other is true and if one is false the other must be false. **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question: `qQuery 3.4.24 write 'all whole numbers are integers' in form 'if p then q'.

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Your solution:

if a number is a whole number, then it is an integer

confidence rating #$&*: 3

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Given Solution:

`a** p could be 'it's a whole number' and q would then be 'it's an integer'. The statement would be 'if it's a

whole number then it's an integer'. **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question: `qQuery 3.4.30 same for ' principal hires more only if board approves

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Your solution:

if the pricipal hires more, then the board appoved

we have to say that the board ""approved"" instead of ""approves"". if we said ""if the principal hires more, then the

board approves"" that makes it sound like the board just approves of whatever the priciple does, not that the

principle must first get their approval

confidence rating #$&*: 3

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Given Solution:

`aCOMMON ERROR WITH INSTRUCTOR COMMENT: If the principal will hire more teachers, then the school board would

approve.

INSTRUCTOR COMMENT:

p only if q is the same as if p then q; should be 'if the principle hires, the school board approved' **

STUDENT COMMENT

I switched the two because I thought the 'only if' meant that was the p part. I thought that it made more sense that

the teacher hiring was dependent on the board approving.

INSTRUCTOR RESPONSE

To say that 'the teacher hiring was dependent on the board approving' would be correct, and would have the same

meaning as the instructor's stated solution.

However the statement 'the teacher hiring was dependent on the board approving' is not equivalent to your statement

'If board approves then the principal hires more', which is not equivalent to the given statement.

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question: `qQuery 3.4.48 true or false: 6 * 2 = 14 if 9 + 7 neg= 16.

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Your solution:

both statements separetely are false, however the statement as a whole is true

since if p then q is only false in the case of if T->F, and both statements are faslse (F->F) the compound statement

is therefore true

confidence rating #$&*: 3

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Given Solution:

`a** Both statments are false, but the compound statement is true.

The compound statement 'p if and only if q' is equivalent to 'if p then q, AND if q then p'.

This compound statement is true because p and q are both false, so 'if p then q' and 'if q then p' are both of form

F -> F and therefore true **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question: `qQuery 3.4.55 contrary or consistent: ' this number is an integer. This number is irrational.'

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Your solution:

the two statements are contrary

we know that all integers are rational numbers and irrational numbers are those numbers that are not rational so

therefore the two statements are contrary

confidence rating #$&*: 3

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Given Solution:

`a**Any integer n can be expressed in the form p / q as n / 1. So all integers are rational.

Irrational numbers are defined as those numbers which are not rational.

So the statements are indeed contrary-it is impossible for a number to be both an integer and irrational. **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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