Question

The average height of 10 pupils is 140cm if a new pupil joined the group the average height of 11 pupils become 148

cm find the height of new pupils ​

Answer 1

228 cm

Explanation:

the average is calculated as

average =
`(sum)/(count)` , then

`(sum)/(10)` = 140 ( multiply both sides by 10 to clear the fraction )

sum = 1400

let the height of new pupil be x , then

`(sum+x)/(11)` = 148 ( multiply both sides by 11 )

sum + x = 1628 , that is

1400 + x = 1628 ( subtract 1400 from both sides )

x = 228

height of new pupil is 228 cm