Average Practice Test 6

Question : 14 of 40

Marks: +1, -0

The average marks of the students in four sections A, B, C and D of a school is 60%. The average marks of the students A, B, C and D individually are 45%, 50%, 72% and Number System and Basic Numeracy 80%, respectively. If the average marks of the students of sections A and B together is 48% and that of the students of B and C together is 60%, what is the ratio of the number of Students in sections A and D?

2 : 3
4 : 3
5 : 3
3 : 5

Validate

Solution:

Average marks of four sections = 60%
Average marks of A, B, C and D sections are 45%, 50%, 72% and 80% respectively.
Average marks of A and B = 48%
By using Allegation approach

Students in Section A = 4, B = 6, C = 5 and D = x
Number of marks = in Section A = 45 × 4 = 180
Section B = 50 × 6 = 300
Section C = 72 × 5 = 360
Section D = 80 × x = 80x

{\Sum \of \mark \obtained \all \sections}/{\Sum \of \student \obtained \all \sections} ={180+300+360+80x}/{15+x}

Average of four sections is 60

={840+80x}/{15+x}

840 + 80x = 900 + 60 x

20 x = 60

x = 3

The ratio of number of students in Sections A and D = 4 : 3

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