Question

Mike drove $30$ miles, at a constant speed, for $t$ hours and then drove $y$ miles, at another speed, for $1$ hour and $15$ minutes. What was his average speed, in miles per hour, for the whole journey?

• A. $(30/t+y/1.25)/2$
• B. $(30+y)/(t+1.25)$
• C. $(30+y)/t$
• D. $(30+y)/1.25$
• E. $(30+y)/2(t+1.25)$

Answer 1

Answer: (B)

$(30+y)/(t+1.25)$

We know that Average speed is given by $d\frac{Totaldistancecovered}{Totaltime}$
We can see that $1$ hour $25$ minutes is equivalent to $1.25hours$

now, from the question we get $Averagespeed=\frac{30+y}{t+1.25}$ as total distance and total time for to and fro is $30+y$ and $t+1.25$ respectively