Question

The mean attendance of a school for the first four days of the week was 780 and for the first five days it was 840 how many were present on fifth day

Answer 1

Step-by-step explanation:

Given  

The mean attendance of a school for the first four days of the week was 780 and for the first five days it was 840 how many were present on fifth day

• Given first five days be D1 D2 D3 D4 and D5
• Now for first 4 days attendance is 780
• Therefore (D1 + D2 + D2 + D4) / 4 = 780
• Or D1 + D2 + D3 + D4 = 3120 --------------- 1
• For first 5 days mean attendance is 840
• Therefore (D1 + D2 + D3 + D4 + D5) / 5 = 840
• Or  D1 + D2 + D3 + D4 + D5 = 4200 ---------------2
• Subtracting 2 – 1 we get
• D5 = 1080

So number of students present on fifth day were 1080

Reference link will be

https://brainly.in/question/6718109

Answer 2

Answer:

Step-by-step explanation:

Explanation:

The formula of average is

average  = sum of entities / total no. of entities

Given,

Average of 4 days attendance  = sum of students present during first 4 days/ 4

sum of students = average x 4

=  3120

Now, we can find out the students present on Friday as

Average attendance of five students = sum of attendance of five students/ 5

Average of five students = sum of students present during first 4 days + present on friday / 5

Thus, students present on friday = (840 x 5) - sum of students present on first four days (3120) = 1080