The average height of 35 students in a class is 4`2``. Three students of average height 4`10`` moved to new section while 6 students of total height 33`4`` joined the class. The average height of the students in the class is now

Correct Answer Is : 4`4``

Solution Is : Total height of 35 students = 50" X 35 = 1750`` total height of 3 outgoing students = 58 X 3 = 174`` Total height of 32 students = 1750 - 174 = 1576`` Total height of 38 students = 1576 + 33 X 12 + 4 = 1976" Required average height = 1976/38 = 52`` = 4`4``

In a class party arranged for 43. students, 26 liked both ice cream and cold drinks, 7 disliked ice cream and 4 disliked both, Then the number of students who liked ice-cream

Correct Answer Is : 32

Solution Is : Required number of students = 43 - 7 = 32

The average marks obtained by a student in 6 subjects is 88. On subsequent verification it was found that the marks obtained by him in a subject was wrongly copied as 86 instead of 68. The correct average of the marks obtained by him is

Correct Answer Is : 85

Solution Is : Correct Average marks = 88-[(86-68)/6] =88-3 = 85

A librarian purchased 50 story-books for his library. But he saw that he could get14 more books by spending Rs. 76 more and the average price per book would be reduced by Re. 1. The average price (in Rs.) of each book he bought, was :

Correct Answer Is : 10

Solution Is :

The average of 7, 11, 15, x, 14, 21, 25 is 15, then the value of x is

Correct Answer Is : 12

Solution Is : 7 +11+15+x+14+21+25 = 15*7;
93+x =105;
x=105 -93 =12.

Correct Answer Is : 38.5

Solution Is : (4) 1²+2²+3²+?+n²
=n(n+1)(2n+1)/6
?Required average
=(n+1)(2n+1)/6
=(10+1)(2×10+1)/6
=(11×21)/16=77/2=38.5

The average of the runs made by Raju, Shyam and Hart is 7 less than that made by Shyam, Had and Kishore. If the number of Kishore`s run is 35, what is Raju`s run ?

Correct Answer Is : 14

Solution Is : (1) Raju+Shyam+Hari=x
Kishore+Shyam+Hari=x+21
Therefore, Runs scored by Raju=35-21=14

The average age of four boys, five years ago was 9 years. On including a new boy, the present average age of all the five is 15 years. The present age of the new boy is

Correct Answer Is : 19 years

Solution Is : Sum of the present ages of four
boys=9*4+20=56 years
Sum of the present ages of five
boys=15*5=75 years
Therefore present age of new boy=75-56=19 years.

If the average of 39, 48, 51, 63, 75, 83, x and 69 is 60, then the value of x is

Correct Answer Is : 52

Solution Is : 39+48+51+63+75+83+x+69=60*8
⇒428+x=480
⇒x=480-428=52

A batsman makes a score of 58 runs in the 15th innings and thus increases his average by 3 runs. What is the average after 15th innings ?

Correct Answer Is : 16

Solution Is : Average before 15th innings =58-15x3=13
Therefore, required average=13+3=16