Question

The mean of seven numbers is 35. If out of these seven numbers, the mean of first four numbers is 33 and the mean of last four numbers is 36, then find the fourth number.
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Answer 1

Answer:

Step-by-step explanation:

Total sum of 7 numbers = 7*35= 245

Sum of first 4 numbers = 33*4 = 132

Sum of last 4 numbers = 36*4 = 144

Total = 144+132 = 276

Fourth number = 276-245 = 31

Answer 2

Fourth number is 31.

Given:

• The mean of seven numbers is 35.
• The mean of first four numbers is 33 and
• The mean of last four numbers is 36.

To find:

• Find the fourth number.

Solution:

Concept /Formula to be used:

$\bf Mean=\frac{\Sigma \: x_i}{n}$

• Fourth number is count twice.

Step 1:

Find the sum of all seven numbers.

Mean= 35

n= 7

Sum of all numbers= 35×7

Sum of all numbers= 245

Step 2:

Find the sum of first four numbers.

Mean= 33

n= 4

Sum of first four numbers= 33×4

Sum of first four numbers= 132

Step 3:

Find the sum of last four numbers.

Mean= 36

n= 4

Sum of last four numbers= 36×4

Sum of last four numbers= 144

Step 4:

Add the results of step 2 and 3.

Sum of numbers(4th number repeated twice)= 144+132

Sum of numbers(4th number repeated twice)= 276

Step 5:

Subtract result of step 4-step 1.

Fourth number= Sum of numbers(4th number repeated twice)-Sum of all numbers

Fourth number = 276-245

Fourth number= 31

Thus,

Fourth number is 31.

Learn more:

1) The mean of 10 numbers is 15 and that of another 20 number is 24 then the mean of all 30 observations is

https://brainly.in/question/3425576

2) The mean of 45 numbers is 25 if each number is multiplied by 3 find the new mean

https://brainly.in/question/4483889