Question

Let the mean of a set of seven numbers be 36. If the mean of the first six numbers is 30, what is the seventh number?
72
6
42
13​

Answer 1

Answer:

72

Step-by-step explanation:

Given-

Mean of set of seven numbers = 36

Let   the  numbers be- x1 ,x2, x3, x4, x5, x6, x7

Mean=  Sum of Observation  /  Number of Observation  

:. Mean= $\frac{x1+x2+x3+x4+x5+x6+x7}{7}$ = 36

x1+x2+x3+x4+x5+x6+x7= 36*7

x1+x2+x3+x4+x5+x6+x7= 252( number 1)

If  one   of   the   number   is   discarded   , then  the mean   of   the remaining  numbers  is  30.

Let   the   discarded   number   be  x7  , then

​Mean= $\frac{x1+x2+x3+x4+x5+x6}{6}$ = 30

x1+x2+x3+x4+x5+x6 = 30*6

x1+x2+x3+x4+x5+x6 = 180(number 2)

On  Subtracting   Number  2    from  Number 1   , we  get

x7= 252- 180

x7 = 72

Hope my answer helped you.........