The average of 30 numbers is 40 and that of other 40 numbers is 30. The average of all the numbers is :
(A) $$34\frac{2}{7}$$
(B) 35
(C) 34
(D) 34.5
Solution:
According to the question,Average of 30 numbers is = 40Sum of 30 numbers is = 40 × 30 = 1200Average of 40 numbers is = 30Sum of 40 numbers is = 40 × 30 = 1200Total average = $$\frac{1200 + 1200}{70}$$= $$\frac{2400}{70}$$ = $$34\frac{2}{7}$$
412.
The average of 7 consecutive odd number is A. If next 4 and previous 3 odd numbers to these 7 odd numbers are also included, then what is the new average of these 14 consecutive odd numbers?
(A) A + 3
(B) A + 4
(C) A + 2
(D) A + 1
Solution:
Average of 7 consecutive odd numbers = A (Given) Then 7 number consecutive odd numbers = - - - A - - - According to the question, If next 4 and previous 3 odd numbers are also included the numbers of terms = 7 + 3 + 4 = 14, and effected sum of numbers = 2 × 7 = 14 ∴ Increment of average $$ = \frac{{14}}{{14}} = 1$$ ∴ Required average = A + 1
413.
Average age of ten persons learning yoga is 32 years. When the age of their instructor is added, the average age becomes 34 years. The age of their instructor is-
(A) 46 years
(B) 52 years
(C) 54 years
(D) 56 years
Solution:
Age of the instructor = (34 × 11 - 32 × 10) years = (374 - 320) years = 54 years
414.
Find the average of all the numbers between 6 and 34 which are divisible by 5 -
The average of 12 numbers is 15 and the average of the first two is 14. What is the average of the rest?
(A) 15
(B) $$15\frac{1}{5}$$
(C) 14
(D) $$14\frac{1}{5}$$
Solution:
Average of 12 numbers = 15 Total of 12 numbers = 15 × 12 = 180 Average of first two number = 14 Total of first two number = 14 × 2 = 28 Total of remaining ten numbers = 180 - 28 = 152 Required average of remaining ten number $$\eqalign{ & = \frac{{152}}{{10}} \cr & = \frac{{76}}{5} \cr & = 15\frac{1}{5} \cr} $$
418.
A has 50 coins of 10 paise denominations. While B has 10 coins of 50 paise denominations. C has 20 coins of 25 paise denominations while D has 25 coins of 20 paise denominations. The average number of paise per person is :
The average score in Mathematics of 90 students of section A and B of class IX was 63. The number of student in A were 10 more that those in B. The average score of student in A was 30% more than that of students in B. The average score of students in B is: