SSC CGL 10 Jun 2019 Shift 1 Paper

Question : 54 of 100

Marks: +1, -0

The average of twelve numbers is 55.5. The average of the first four numbers is 53.4 and that of the next four numbers is 54.6. The 10

^{\th}

number is greater than the 9

^{\th}

number by 3 but lesser than the 11

^{\th}

and 12

^{\th}

numbers by 2 and 3, respectively. What is the average of the 10

^{\th}

and the 12

^{\th}

numbers?

Solution:

Sum of twelve numbers

=55.5 \× 12=666

Sum of first

4=53.4 \× 4=213.6

Sum of next four

=54.6 \× 4=218.4

Let

10^{\th}

number be x
So,

9^{\th}=x-3 ; 11^{\th}=x+2

12^{\th}=\ {x}+3

So ,

213.6+218.4+(x-3)+x

+(x+2)+(x+3)

=666

\⇒432+4 x+2=666

⇒x=58

10^{\th}=58,12^{\th}=61

Average of

10^{\th}\ \&\ 12^{\th}=59.5

Go to Question:

Prev Question

Next Question