Q16. The average price of three items of further is Rs. 15000. If their prices are in the ratio 3:5:7, find the price of cheapest item.
a) Rs 11000
b) Rs 15000
c) Rs 4500
d) None of these
A. (d)
Let the prices given in ratio be 3x, 5x and 7x.
So,
3x + 5x + 7x = 15000 * 3
15x = 45000
x = 3000
Cheapest item = 3x = 3 * 3000 => 9000 Rs.
Q17. The average age of 8 men is increased by 2 years when two of them whose ages are 21 years and 23 years are replaced by two new men. Find the average age of two new men.
a) 30
b) 35
c) 25
d) (a)
None of these
A. Total age increased = 2 * 8 => 16 years
Sum of ages of two new men = 21 + 23 + 16 = 60 years
So, average age = 60/2 => 30 years.
Q18. The average age of ram and his wife sita was 23 years at the time of their marriage. After five years, they have 1 child whose age is 1 year. Find the average age of family now.
a) 57
b) 26
c) 19
d) None of these
A. (c)
Summing up the present age of ram, sita and child:
(23*2 + 5*2) + 1
57 years
Now, average age = 57/3 = 19 years.
Q19. Three years before, average age of a family of 5 members was 17 years. A baby having been born the average age of family is same today. Find the present age of baby.
a) 102
b) 100
c) 112
d) None of these
A. (d)
Total age of family before 3 years = 17*5 = 85 years
Total age of family now (5 member) = 85 + 15 => 100 years.
Sum of present age of family = 17*6 = 102 years
Age of baby = 102 – 100 => 2 years.
Q20. In a college with 600 students, average age of boys is 12 years and that of the girls is 11 years. If the average age of the college is 11 years 9 months, then find the number of girls.
a) Rs 160
b) Rs 170
c) Rs 180
d) None of these
A. (d)
Let the number of girls be x.
So, number of boys will be 600 – x.
Then
11.9 * 600 = 11x + 12(600-x)
7140 = -x+ 7200
x = 150.