Question

The mean of 5 numbers is 10 2.The mean of the 4 of these number is 10.Find the 5th number​

Answer 1

its a little bit confusing that if the mean of five no.'s is 10 or 102.

OK

i) if the mean of five no's is 102 then

(a+b+c+d+e) / 5 = 102

a+b+c+d+e = 510 & also the mean of 4 no.'s is 10 therefore, (a+b+c+d)/4 = 10

a+b+c+d = 40

hence, (a+b+c+d)+e = 510

40+e = 510

»[e = 470].

ii) if the mean of five no.'s is 10 then

(a+b+c+d+e) / 5 = 10

(a+b+c+d)+e = 50

40+e = 50

»[e = 10].