Question

The average value of five numbers is 40. If a number is deleted from the five numbers, then the average will be reduced by 10. Find the deleted number​

Answer 1

Answer:

Mean = sum/no. of observations

40 = sum / 5

sum1 = 40 × 5 = 200

Now one number is deleted,

Mean = 40 - 10 = 30

30 = sum / 4

sum2 = 30 × 4 = 120

The number which is deleted = sum1 - sum2

= 200 - 120

= 80

Pls follow....

Answer 2

Answer:

The deleted number  = 80

Step-by-step explanation:

Given,

The average of five numbers  = 40

A number is deleted from the five numbers, the average will be reduced by 10.

To find,

Find deleted number

Solution:

Average = $\frac{Sum \ of \ observations}{Total\ number \ of \ observations}$ -------------------(1)

Since average = 40 and number of observations = 5

Sum of five numbers = Average × Total number of observations

= 40 × 5

= 200

Let 'x' be the number deleted,

The sum of observations when the number 'x' is deleted = 200 - x

Total number of observations when the number 'x' is deleted = 4

Since the average is reduced by 10, the average of 4 observations

= 40 - 10

= 30

Hence from equation (1), we have

30 = $\frac{200 - x}{4}$

200 -x = 30 ×4 = 120

x = 200 - 120

= 80

∴ The deleted number  = 80

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