Average - Study Mode
[#151] The average of 6 numbers is 7. The average of three numbers of them is 5. What will be the average of remaining numbers?
Correct Answer
(C) 9
Explanation
Solution: Average of 6 numbers = 7 Sum of 6 numbers = 6 × 7 = 42 Average of three numbers = 5 Sum of three numbers = 5 × 3 = 15 ∴ Sum of the remaining three numbers = 42 - 15 = 27 ∴ Required average = $$frac{27}{3}$$ = 9
[#152] Find the average of 205, 302, 108, 403, and 202-
Correct Answer
(C) 244
Explanation
Solution: Sum of numbers = 205 + 302 + 108 + 403 + 202 = 1220 ∴ Required average = $$frac{1220}{5}$$ = 244
[#153] The average age of 7 members of a family is 40 years. In the family, there are three men, three women and one boy. If the average age of three men is 48 years and average age of three women is 44 years, then the age of the boy is:
Correct Answer
(C) 4 years
Explanation
Solution: According to the question, Let the age of boy be x 7 × 40 = 3 × 48 + 3 × 44 + 1 × x 280 = 144 + 132 + x x = 4 Therefore, age of the boy is = 4 years
[#154] The average of marks obtained by A and B is 15 less than that of average marks obtained by B and C. If the marks obtained by C is 65, What is the marks obtained by A?
Correct Answer
(A) 35
Explanation
Solution: $$eqalign{
& { ext{According to the question,}} cr
& left( {frac{{B + C}}{2}}
ight) - left( {frac{{A + B}}{2}}
ight) = 15 cr
& Rightarrow frac{{B + C - A - B}}{2} = 15 cr
& Rightarrow frac{{C - A}}{2} = 15 cr
& Rightarrow C - A = 30 cr
& C = 65 cr
& herefore A = 35 cr} $$
[#155] The numbers of students in section A and section B of a class are 50 and 62, respectively. The average score in mathematics of all students is 75. If the average score of students in section A is 20% more than that of students in section B, then what is the average score of students in section A (correct to
one decimal place)?
Correct Answer
(C) 82.6
Explanation
Solution: 20% = $$frac{1}{5}$$ Let, average marks of section B = 5x Average marks of section A = 6x Total marks = 50 × 6x + 62 × 5x = (50 + 62) 300x + 310x = 112 × 75 610x = 8400 x = $$frac{{840}}{{61}}$$ Average marks of section A students = 6x = 6 × $$frac{{840}}{{61}}$$ = 82.6