Question

three numbers have mean of 64 when a fourth number is included the mean is doubled what is the fourth number​

Answer 1

Step-by-step explanation:

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Answer 2

Answer:

320

Step-by-step explanation:

formula for mean=sum of number/number of number

mean of three numbers viz, a b c=a+b+c/3=64

so a+b+c=64x3=192

mean of 4 numbers(let 4th number be d)=a+b+c+d/4=128 as the mean is doubled

a+b+c+d=128x4=512

and we know a+b+c+=192

so d=512-192=320

even checking twice= 192+320/4=128

192=a+b+c so instead of doing a+b+c+320/4    we did 64+320/4