Question

While writing 20 numbers two numbers were wrongly written as 52 and 27 in place of 25 and 72 and the main thus obtained by 50 then find the correct mean

Answer 1

Answer:

50.9

Step-by-step explanation:

let the sum of the rest of 18 numbers be X

then given,

(X+52+27)/20 = 50

X+79 = 1000

X = 921

when the correct numbers are added:-

mean = (X+25+72)/20

= (921+25+72)/20

= 1018/20

= 50.9

Answer 2

Answer:

50.9

Step-by-step explanation:

sum of all 20 numbers= 50×20= 1000

sum of remaining 18 numbers +(52+27) = 1000

= sum of only 18 numbers= 1000-79= 921.

=> sum of 18 numbers+(25+72)= 921+97= 1018

=> average= 1018/20 = 50.9

shortcut method

original mean = [50×20+( 25+72)-(52+27) ] / 20

= (1000+97-79) /20

= 1018/20

= 50.9

Answer