Question

Mean of 10 numbers was found to be 40 later it was detected that number 45 was misread as 15 find the correct mean

Answer 1

mean= [(sum of all no.) / (total no.)]

let sum of all numbers= x1+x2.....+x9+15
putting in formula we get,

40= [(x1+x2.....+x9+15) / 10]

from this we get,

(x1+x2.....+x9+15) = 400

x1+x2.....+x9 = 400-15

x1+x2......+x9 = 385_______(1)

now according to question,
45 was misread as 15 so. using formula for mean we get,

new mean=[(x1+x2.....+x9+45) / 10]

new mean = [(385+45) / 10]

new mean = 430/10


new mean = 43




hope this helps you