The mean attendance (out of 90 days) of the students of section 'A' and section 'B' in class VII are 70 and 73 respectively. If the mean attendance of all the students of class VIll is 71, find the ratio of the number of students from section 'A' to the number of students from section 'B'.
Answers
Given : The mean attendance (out of 90 days) of the students of section 'A' and section 'B' in class VII are 70 and 73 respectively.
mean attendance of all the students of class VIl is 71,
To Find : the ratio of the number of students from section 'A' to the number of students from section 'B'.
Solution:
Let say student in section A = A
Mean attendance = 70
Total attendance of section A = 70A
Students in Section B = B
Mean attendance = 73
Total attendance of section B= 73B
Total attendance of class = 70A + 73B
Total Students of class = A + B
Mean = 71
Total attendance of class = 71 ( A + B)
= 71A + 71B
70A + 73B = 71A + 71B
=> 2B = A
=> A = 2B
=> A/B = 2
=> A : B = 2 : 1
ratio of the number of students from section 'A' to the number of students from section 'B'. = 2 : 1
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Answer:
- The mean attendance (out of 90 days) of the students of section 'A' and section 'B' in class VII are 70 and 73 respectively.
- Mean attendance of all the students of class VIl is 71.
Section A ⠀⠀⠀ ⠀⠀⠀Section B
⠀⠀70 ⠀⠀⠀ ⠀⠀⠀ ⠀⠀⠀ 73
⠀⠀⠀ ⠀⠀⠀⠀Mean
⠀⠀⠀ ⠀⠀⠀ ⠀ 71
⠀(73 - 71)⠀⠀⠀⠀:⠀⠀⠀⠀⠀(71 - 70)
⠀⠀2 ⠀⠀⠀ ⠀⠀⠀: ⠀⠀⠀ ⠀⠀ 1
Hence, the Required of the number of students from section 'A' to the number of students from section 'B' is 2:1