It's a math word problem

Question

A family-size box of laundry detergent is 72 oz. The regular-size box is 25% smaller. Both boxes of detergent cost 5 cents per ounce. Is $2.70 a reasonable price for the regular-size box?

Answer 1

YES, because the regular box would be 54 oz (3/4 the weight of the family size box).  5 cents per ounce times 54 ounces is exactly $2.70.

Answer 2

Hi Grace,

 

We can determine if $2.70 is a reasonable price for the regular-size box by finding how much it should cost, given that detergent costs 5cents, or $.05 per ounce.

 

How many ounces is the regular-size? We know:

 

the family size box is 72oz.

 

the regular-size box is 25% smaller.

 

well, 25% of 72 is .25*72 = 18.

 

So, since the regular-size box is 25% smaller, it is 18oz smaller.

 

72oz - 18oz = 54oz.

 

Now we know how many oz the regular box is.

 

We also know, again, it is $.05 per oz, and there is 54 oz.  Then, the total cost is 54*.05=2.7. In dollars, this is $2.70.

 

So, 2.70 is reasonable price to pay.