Ques 1.
The average age of six boys is 13 years. If the age of one more boy is added to it, the average age increases by one year. What is the age of the new boy?
Solution :
New Boy Age = Old Average + (Total Members * Increased Average)
New Boy Age = 13 +(7*1) = 13+7=20 years
Ques 2.
A fruit seller sells 4 oranges for a rupee and makes a profit of 25%. How many oranges did he buy for a rupee?
Solution :
Selling price = 1/4
Cost Price = 1/x
1/4 --------- 125%
1/x -------- 100%
x= 5
Ques 3.
If A’s salary is 40 % more than B’s, how much per cent is B’s salary less than A’s
Solution :
Take B is 100, A is 40 more than B so A is 140
Now take 140 --------- 100%
100 --------- x%
==» x = 500/7 %
B is (100-x)% less than A
= 100 -(500/7) = 200/7 %
Ques 4.
A man is 24 years older than his son. In two years, his age will be twice the age of his son. What is the present age of his son?
Solution :
Assume Son is " X"
Then father age is " X + 24 "
After 2 years :
Son age became " X+2"
Father age became " X+24+2" = X + 26
From the question, After 2 years hence father age is twice to Son age
==> 2(X+2) = (X+26)
==> X = 22 years
Ques 5.
An error 5 % in excess is made while measuring the side of a square. What is the percentage of error in the calculated area of the square?
Solution :
Percentage change in Area = 5+5+(5*5)/100
==> 10+0.25=10.25%
Ques 6.
An error 2 % in shortcoming while measuring the side of a square. What is the percentage of error in the calculated area of the square?
Solution :
Percentage change in Area = (-2)+(-2)+((-2)*(-2)/100
==> -4+0.04 = -3.96%
Note : " - " represents decreasing here
Ques 7.
A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is:
Solution :
Speed of Man Against current = speed of man with current - 2*( speed of stream)
==> Speed of Man Against current = 15- 2*(2.5) = 10kmph
Ques 8.
X and Y invest Rs.21000 and Rs.17500 respectively in a business. At the end of the year, they make a profit of Rs.26400. What is the share of X in the profit?
Solution :
X and Y profit ratio = ( X investment * Time) : ( Y investment * Time)
= (21000*1) : (17500*1)
X : Y = 6:5
Total profit = 26400 ( its equal to 6+5 = 11parts)
11 parts ---------- 26400
6 parts ----------- ?
X profit share = (26400*6)/11 =14400
Ques 9.
Out of 8 consonants and 4 vowels, how many words of 4 consonants and 2 vowels can be formed?
Solution :
Number of ways of selecting 4 consonants from 8
= 8C4
Number of ways of selecting 2 vowels from 4
= 4C2
Number of ways of selecting 4 consonants from 8 and 2 vowels from 4
= 8C4 × 4C2 = 420
It means we can have 420 groups where each group contains total 6 letters (4 consonants and 2 vowels) .
Number of ways of arranging 6 letters among themselves
Hence, required number of ways
= 6! = 6×5 × 4 × 3 × 2 × 1 = 720
Hence, required number of ways = 720 * 420 = 302400
Ques 10.
Kevin buys an old scooter for Rs. 4700 and spends Rs. 800 on its repairs. If he sells the scooter for Rs. 5800, what is his gain percent?
Solution :
Total cost = 4700+800 = 5500
Selling price = 5800
Profit = 5800- 5500 = 300
Profit percentage = (profit)/(cost price) * 100
==>> 300*100/5500 = 60/11 %
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