Question

Julie drives 100 mi to Grandmother's house. On the way to Grandmother's, Julie drives half the distance at 38.0 mph and half the distance at 62.0 mph. On her return trip, she drives half the time at 38.0 mph and half the time at 62.0 mph.A) What is Julie's average speed on the way to grandmother's house?B) What is her average speed in the return trip?

Answer 1

46.95 mph

50 mph

Step-by-step explanation:

first, we start by finding the average speed. The average speed if given by the relation

Average Speed = Total distance / Total Time

from the question, we know that

total distance is 100 mi

total time is time of the first distance + time of the second distance

t = (50mi / 38) + (50mi / 62)

t = 1.32 + 0.81

t = 2.13 hrs

Then, the average speed going to grandmothers house will be

Speed = 100mi / 2.13 hrs

Speed = 46.95 mph

on her return trip

speed on the first distance * half the time + speed on the second distance * half the time

x = V1 * t/2 + V2 * t/2

100 = 38 * t/2 + 62 * t/2

100 = 100 * t/2

t/2 = 100/100

t/2 = 1

t = 2 hrs

The average speed then will be, = 100 mi / 2 hrs = 50mph

Answer 2

A.46.7mph

B.50mph

Step-by-step explanation:

We know that from the data given

Julie drove 50 miles at a speed of 38 mph, and another 50 miles for 62mph. Thus , for the first 50 miles, she drove for the following time

T1= distance/speed

====> 50/38= 1.3hrs

the next 50 miles, she drove for

T2= 50/62

= 0.8hrs

So average speed is

Totaldistance/ total time

100/2.1

= 46.7mph

B. Because the time she used driving at 35 mph is the same amount of time she used driving at 65 mph, the average speed is just the average of the two speeds given which is

(50+50)/2 = 50mph

Step-by-step explanation: