SSC CGL 4 06 2019 Shift 1 Paper

Question : 63 of 100

Marks: +1, -0

The average of twelve numbers is 42. The average of the last five numbers is 40, and that of the first four numbers is 44. The 6

^{\th}

number is 6 less than the fifth and 5 less than the 7

^{\th}

number. The average of the 5

^{\th}

and the 7

^{\th}

numbers is

Solution:

Sum of 12 numbers

=42 \×12=504

um of last 5 numbers

=5 \×40=200

um of last 4 numbers

=4 \×44=176

Let 5

^{ {\th }}

number be

x

then, 6

^{ {\th }}

number will be

(x-6)

and, 7

^{ {\th }}

number will be

(x-1)

\∴ 176+200+x+(x-6)+(x-1)=504

\⇒x=45

∴

\ 5^{ {\th }}

number

=45

^{ \th}

number

=39

^{ \th}

number

=44

\∴

Average of

5^{ {\th }} \& 7^{ {\th }}

number

=\ {45+44}/{2}=44.5

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