Question

What is the value of 8.0 km in inches?

(1 m = 1.1 yards & 1 yard = 36 inches)

• A. $3.16\times {10}^5$
• B. $3.2\times {10}^5$
• C. $3.1\times {10}^5$
• D. $3.168\times {10}^5$

Answer 1

The correct option is B $3.2\times {10}^5$

8 km = 8 $\times$1000 m
$\to$ 8 $\times$ 1000 $\times$ 1.1 yards
$\to$ 8 $\times$ 1000 $\times$ 1.1 $\times$ 36 inches
= 3.168 $\times$ ${10}^5$ inches
Since 8.0 has two significant digits we report the answer in two significant figures after rounding off i.e.,
3.2 $\times$ ${10}^5$ inches