Which of the following quantities are inversely proportional?
option 1: the height of a rectangular prism and the area of its base, if the volume is 56 in3
option 2: the amount of time spent plowing a field and the amount of fuel used by a tractor
option 3: the length of fabric bought for $74.50 and the price of one yard
option 4: the amount of time spent plowing a 358-acre farm and the number of identical tractors

Option 1

Option 3

Option 4

Step-by-step explanation:

Inversely proportional means "one quantity increases, the other decreases" or "one quantity decreases, other increases". Inverse relationship, that's it.

Option1:

Since the volume is given as 56 and we know the volume is area of base * height, to keep the volume at constant [56], if height increases, area of base would need to decrease, and vice verse. So inversely proportional.

Option2:

The time spend in plowing a field with a tractor will increase when we area using more fuel. So more fuel used means more time spent. So these are directly proportional, NOT inverse.

Option3:

Since the price is at constant, the amount of length we buy more, the price per one yard HAS to decrease, and vice versa. So, this is inverse relationship.

Option 4:

If the number of identical tranctors increase, it will take less time to plow the set 358 acre farm. And vice versa. So this is inversely proportional as well.

to determine the unit cost your would divide the total cost by the number sold.

7 bagels for $4.41       $4.41/7 = $.63 each at fresh side

5 bagels for $3.60         $3.60/5 = $.72 each at value mart