The radius of a sphere is measured as `(2.1 pm 0.5)cm`. Its surface area with error limits is :

Options

A. `(55.4 pm 23.4)cm^(3)`
B. `(55.4pm 26.4)cm^(2)`
C. `(55.4 pm 22.4)cm^(2)`
D. `(55.5 pm 22.6)cm^(2)`

Answer

B

Explanation

Radius of a sphere `=(2.1 pm 0.5)cm`
`r=2.1 cm`
`Deltar=0.5`
Surface area `=4pir^(2)`
`=4xx3.14xx2.1xx2.1`
`=55.4cm^(2)`
`(Deltas)/(s)= pm (2Deltar)/(r ) = pm (2xx0.5)/(2.1)`
`Deltas=pm (2xx0.5)/(2.1)xx55.4`
`=pm 26.4 cm^(2)`
Error limits `=(55.4 pm 26.4)cm^(2)`