Question

Emily leaves her house at exactly 8:25 AM, to bike to her school which is 3.42 miles away. When she passes the post office, which is 3/4 mile away from her home, she looks at her watch and sees that it's 30 seconds past 8:29 AM. If Emily's school starts at 8:50 AM, can she make it to school without increasing her current rate of speed?

Answer 1

Speed used by Emily from home to post office is:
speed=(distance)/(time)
distance=3/4 miles
time=8:29:30-8:25=4 min 30 sec=4.5 min
thus speed=(0.75)/4.5=1/6 mile/min

The remaining distance from Post office to school:
3.42-0.75=2.67 miles
time taken to reach to school assuming that Emily will move with the same speed is:
time=2.67/(1/6)=16.02 min=16 min 1.2 seconds
time Emily will reach school is:
8:29:30+0:16:1.2
=8:45:31 a.m
This means that she will reach on time