Question

The least count of a stopwatch is $\frac{1}{5}$ sec. The time of $20$ oscillations of a pendulum is measured to be $25$ sec. The maximum percentage error in this measurement is :

• A. $8$%
• B. $1$%
• C. $0.8$%
• D. $16$%

Answer 1

The correct option is C $0.8$%

$Error$ % $=\frac{△t}{t}\times 100$
$△t=leastcount$
$t=25sec$

$\Rightarrow \frac{1/5}{25}\times 100=\frac{100}{125}=\frac{4}{5}=0.8$%