Question

When Mr. Peters drives from Boston to Worcester it takes him 30 minutes travelling at a speed of 60 miles per hour. Mrs. Peters drives from Boston to Worcester and leaves 5 minutes after Mr. Peters but travels at a speed of 90 miles per hour. Who will arrive first? By how many minutes?

Answer 1

Answer:

Ms.P will arrive 5 minutes before Mr.P

Step-by-step explanation:

Answer 2

Since the problem is requesting the answer in minutes, we are going to convert the speed of Mr. Peter to miles per minutes; to do that, we are going to multiply his speed by the multiplier $\frac{60min}{1h}$:
$60 \frac{miles}{h} * \frac{1h}{60min} =1 \frac{mile}{min}$

Now, to find the distance from Boston to Worcester, we are going to use the distance formula: $d=vt$
where
$d$ is the distance
$v$ is the speed
$t$ is the time 

We know that the speed of Mr. Peter is $1 \frac{mile}{min}$ and his time is 30 minutes. Lets replace those values in our formula:
$d=1 \frac{mile}{min} *30min$
$d=30miles$

Now, lets concentrate on Mr. Peter clone, Mr. P:
Lets convert the speed of Mr. P to miles per minute:
$\frac{90miles}{h} * \frac{1h}{60min} =1.5 \frac{miles}{min}$
We also know that they will cover the same distance, 30 miles. Lets replace the values in our formula one more time to find t:
$d=vt$
$30miles= 1.5\frac{miles}{min} *t$
$t= \frac{30miles}{1.5\frac{miles}{min}}$
$t=20min$
But since Mr. P leaves 5 minutes after Mr. Peters, we need to add those 5 minutes to M. P's time:
$t=20min+5min$
$t=25min$

We can conclude that Mr. P will arrive first, 5 minutes before Mr. Peter.