Based upon the data set, which statement is true?

Question

A-   10    3   15
B-    5     8   10
C-   3     16   4
 
A) A varies jointly with B and C
B) B varies jointly with A and C
C) C varies jointly with A and B
D) C varies directly with A and inversely with B

Answer 1

I think writing this question like this is easier to understand:

 

A    B   C

10  5    3

3    8   16

15  16  4

 

A) "A varies jointly with B and C" means  A = k*B*C

B) "B varies jointly with A and C" means B = k*A*C

C) "C varies jointly with A and B" means C = k*A*B

D) "C varies directly (same as jointly) with A and inversely with B" means C = k*A/B

 

Substitute The values in for A, B and C to find the value of k for each question.

 

Example:

 

A) k = A/(B*C) = 10/(5*3) = 10/15 = 2/3 then substitute all the numbers into the k*B*C equation to find if they = A

 

3 = 2/3*8*16 is not true so it is not A)

 

Continue these steps for B, C and D.

 

Hint: You will find the true statement before getting to statement D.