Question

A student in the laboratory measures thickness of a wire using screw gauge. The readings are 1.22 mm, 1.23 mm, 1.19 mm and 1.20 mm. The percentage error is $\frac{x}{121}$%. The value of x is _________.

Answer 1

The correct answer is 150.
Imean =$\frac{1.22+1.23+1.19+1.20}{4}=1.21$
ΔImean =$\frac{0.01+0.02+0.02+0.01}{4} =0.015$
So %I=$\frac{ΔI_{mean}}{I{mean}}$ ×100=$\frac{0.015}{1.21}$×100 =$\frac{150}{121}$%
x= 150
So, value of x is 150.