SSC CHSL 5 Aug 2021 Shift 3 Paper

Section: Quantitative Aptitude

Question : 68 of 100

Marks: +1, -0

The average height of a certain number of students in a group is

155.6 {cm}

. If 12 students having an average height of

150.5 {cm}

join the group and 7 students having an average height of

159 {cm}

leave the group, the average height of the students in the group will decrease by

34 {mm}

. What is the number of students, initially, in the group?

Solution:

Let the number of students initially in the group be

x

.
According to the question,

x × 155.6+12 × 150.5-7 × 159

=(x+5)(155.6-3.4)

⇒ 155.6 x+1806-1113

=155.6 x-3.4 x+778-17

⇒ \;\; 693=-3.4 x+761

⇒ \;\; 3.4 x=68

∴ \;\; x=\;{68}/{3.4}=20

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