Question

A train is traveling at 60 mph. If the rate of speed increases 4 mph each hour, how long will it be before the train is traveling at a rate of 80 mph?
A. 4 hours
B. 5 hours
C. 6 hours
D. 7 hours

Answer 1

Answer:

B. 5 hours

Step-by-step explanation:

If the train is going 60mph and we need to find out how long it will be until it is traveling 80mph then we have to do 80-60=20 to figure out how much the speed is changeing. Since every hour the speed increases by 4mph then we have to do how much the train is increasing divided by how much it increases per hour.

20÷4=5

Therefore it will take 5 hours

Answer 2

Answer:

B. 5 hours

Step-by-step explanation:

80-60 = 20

So we need to find how long it takes to increase 20 mph.

at a rate of y = 4x + 60

y = 4(2) + 60 = 68 nope.

y = 4(3) + 60 = 72 nope.

y = 4(4) + 60 = 76 nope.

y = 4(5) + 60 = 80 yep.

Or you could do 20/4 = 4