model 1 basic average questions Practice Questions Answers Test with Solutions & More Shortcuts

Question : 1 [S.S.C. (CHSL) 2011]

The average of x numbers is y and average of y numbers is x. Then the average of all the numbers taken together is

a) $\text"x+y"/\text"2xy"$

b) $\text"2xy"/\text"x+y"$

c) $(x^2+y^2)/\text"x+y"$

d) $\text"xy"/\text"x+y"$

Question : 2 [S.S.C. (CISF) 2011]

If average of 20 observations x₁,x₂, ....., x₂₀ is y, then the average of x₁ – 101, x₂ – 101, x₃ –101, ....., x₂₀ –101 is

a) y-20

b) y-101

c) 20y

d) 101y

Question : 3 [S.S.C. (CHSL) 2011]

The average of $x$ numbers is $y^2$ and the average of $y$ numbers is $x^2$. So the average of all the numbers taken together is

a) $(x^3+y^3)/\text"x+y"$

b) $xy$

c) $(x^2+y^2)/\text"x+y"$

d) $xy^2+yx^2$

Question : 4 [S.S.C. (CGL) 2016]

In a class, average height of all students is ‘a’ cms. Among them, average height of 10 students is ‘b’ cms and the average height of the remaining students is ‘c’ cms. Find the number of students in the class. (Here a > c and b > c )

a) $(a(b-c))/(a-c)$

b) $(b-c)/(a-c)$

c) $(b-c)/\text"10(a-c)"$

d) $\text"10(b-c)"/(a-c)$

Question : 5 [S.S.C. (CGL) 2015]

Average of n numbers is a. The first number is increased by 2, second one is increased by 4, the third one is increased by 8 and so on. The average of the new numbers is

a) $a+(2^(n-1)-1)/n$

b) $a+2(2^n-1)/n$

c) $a+2^(n-1)/n$

d) $a+(2^n-1)/n$