Chapter 2, Problem 8STP

To determine

To Choose: The correct option.

Answer to Problem 8STP

A correct answer is an option (C).

Explanation of Solution

Given:

The given table is shown below

Runner	Distance covered (km)	Time (min)
Ling-Long	12.5	42
LaToya	7.8	38
Bill	10.5	32
Jose	8.9	30

Formula used:

The average speed is

  $s=\frac{d}{t}$  ...... (1)

Here, $d$ and $t$ are distance and time taken to travel.

Calculation:

Substitute 12.5 km for $d$ and 42 min for $t$ in equation (1) for Ling-Ling’s average speed

  $\begin{array}{l}s=\frac{12.5\text{km}}{42\min }\\ \boxed{s=0.30\text{km/min}}\end{array}$

Substitute 7.80 km for $d$ and 38 min for $t$ in equation (1) for LaToya’s average speed

  $\begin{array}{l}s=\frac{7.8\text{km}}{38\min }\\ \boxed{s=0.20\text{km/min}}\end{array}$

Substitute 10.5 km for $d$ and 32 min for $t$ in equation (1) for Bill’s average speed

  $\begin{array}{l}s=\frac{10.5\text{km}}{32\min }\\ \boxed{s=0.33\text{km/min}}\end{array}$

Substitute 8.9 km for $d$ and 30 min for $t$ in equation (1) for Jose’s average speed

  $\begin{array}{l}s=\frac{8.9\text{km}}{30\min }\\ \boxed{s=0.30\text{km/min}}\end{array}$

From the above calculation, it is evident that Bill has fastest average speed.

Conclusion:

Hence, Bill has fastest average speed.