From 8:25 am to 30 seconds past 8:29 am, there are 4.5 minutes. Her speed is calculated by dividing the distance of the post office from her house by the time.
Speed = 0.75 mile / 4.5 minutes = 1/6 mile / minute
Determining the number of minutes she will have to take in order to reach school,
Time = 3.42 mile / (1/6 mile/minute) = 20.52 minutes
Adding this to the initial time,
Final time = 8:25 am + 20.52 minutes
= 8:45 am and 31.2 seconds.
She will reach the school on time even without increasing her speed.
