Question

Suppose that y varies directly with x and inversely with z, and y = 18 when x = 15 and z = 5. Write the equation that models the relationship. Then find y when x = 21 and z = 7

Answer 1

@Hero

Answer 2

Hint:
If y varies directly with x and inversely with z, then:

yz = kx

Input the given values to find k

Answer 3

18(5) = k(15)?

Answer 4

Yes, now solve for k:
(18*5)/15 = k

Answer 5

here are the multiple choice answers.

y = 5z/x; 5/32
t = 5x/z;15
t = 6x/z;18
t = 6z/x;2

Answer 6

Solving for k is only part of the problem. Find k, then get back to me.

Answer 7

OK 18 * 5 IS 90/15 = k

k = 6 @hero

Answer 8

Okay, good. Now you have to use this formula again:

yz = kx

except this time use the fact that k = 6, x = 21, and z = 7 to find y

Answer 9

y(7) = 21*6

7y = 126
y = 18

Answer 10

GJ

Answer 11

thanks so the answer
t = 6x/z;18

Answer 12

@hero

Answer 13

I don't know where t comes from.

Answer 14

If you have to choose one, then I suppose what you have chosen is correct.

Answer 15

alright is there another way to solve this? that might give a different answer? @Hero

Answer 16

There's only one way to solve it, and I have shown it to you. Your math course is being weird. Trust me. 99% of the world does it the way I've shown you (without the t)

Answer 17

But don't worry. Your answer choice should be correct.

Answer 18

alright thanks hun :P