Question

the mean of 20 numbers is 17, if 3 is added to each number , then the new mean is ?

Answer 1

Mean of 20 numbers = 17.
Sum of 20 numbers = (17×20) = 340.
Since, 3 is added to each number, the sum is increased by (20×3)=60.
Sum of the 20 numbers becomes (340+60) = 400.
Hence, the new mean of 20 numbers = (400÷20) = 20.  (Ans.)

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Answer 2

let x be the sum of the numbers
x/20=17
x=20*17
x=340
the total number of numbers taken into consideration=20
when 3 is added to each of them the increase=20*3
so,
new average=(340+60)/20
                  =400/20
                  =20