Question

Which situation results in a final value of exactly zero? A The temperature outside was 15 degrees below 0 at 7:00 a.m. The temperature rose 3 degrees each of the next 4 hours. B Hector earned $7:40 for each of 8 hours of work. He used $60 of this money to buy video games. C Mrs. Kaplan received an order to bake 120 cookies. She completed the order by baking 24 cookies every 30 minutes over a period of 5 hours. D A runner ran up hill during 2.4 minutes at a rate of 30 feet per minute. The runner ran downhill diring 1.2 minutes at a rate of 15 feet per minute.

Answer 1

A ) 15degrees below 0 is -15degrees. 3 x 4 = 12. So -15 + 12 = -3. Therefore, A does not equal the value of 0

B) $7.40 x 8 = $59.20. $59.20 - $60 = -$0.80. Therefore, B does not equal the value of 0.

C) 30 mins is equivalent to 1/2 of 1hr. 24 x 0.5 = 12
If 30 mins = 1/2 hour and its over period of 5 hours then a shortcut to solve this would be 10(12) ,as double the amount of 5 is 10. 10 x ( 24 x 0.5) in short = 10(12)
10x12 = 120
Therefore C equals exact value of 0

D) (just for proof) 2.4 x 30 = 72 , 1.2 x 15 = 18
72-18 = 54. Therefore, D does not equal the value of 0