Quantitative Aptitude
AVERAGES MCQs
Averages
Total Questions : 3752
| Page 371 of 376 pages
Answer: Option B. -> Rs.18
AVERAGE PRICE PER BOOK = (1150 + 920) / (65 + 50) = 2070 / 115 = RS.18
AVERAGE PRICE PER BOOK = (1150 + 920) / (65 + 50) = 2070 / 115 = RS.18
Answer: Option A. -> 75
LET THE MARKS OBTAINED BY THE STUDENT IN PHYSICS, CHEMISTRY AND MATHEMATICS BE P, C AND M RESPECTIVELY.
P + C + M = 150 + P
C + M = 150
AVERAGE MARK OBTAINED BY THE STUDENT IN CHEMISTRY AND MATHEMATICS = (C + M)/2 = 150/2 = 75
LET THE MARKS OBTAINED BY THE STUDENT IN PHYSICS, CHEMISTRY AND MATHEMATICS BE P, C AND M RESPECTIVELY.
P + C + M = 150 + P
C + M = 150
AVERAGE MARK OBTAINED BY THE STUDENT IN CHEMISTRY AND MATHEMATICS = (C + M)/2 = 150/2 = 75
Question 3703. The present average age of a family of five members is 26 years. If the present age of the youngest member in the family is ten years, then what was the average age of the family at the time of the birth of the youngest member ? (Assume no death occurred in the family since the birth of the youngest).
Answer: Option C. -> 20 years
PRESENT TOTAL AGE OF THE MEMBERS = 26(5) = 130 YEARS.
PRESENT AGE OF THE YOUNGEST MEMBER = 10 YEARS
PRESENT TOTAL AGE OF THE REMAINING FOUR MEMBERS = 130 -10 = 120 YEARS
THEIR AVERAGE AGE AT THE TIME OF THE BIRTH OF THE YOUNGEST MEMBER = [120 – (4 * 10)] / 4 = 30 – 10 = 20 YEARS
PRESENT TOTAL AGE OF THE MEMBERS = 26(5) = 130 YEARS.
PRESENT AGE OF THE YOUNGEST MEMBER = 10 YEARS
PRESENT TOTAL AGE OF THE REMAINING FOUR MEMBERS = 130 -10 = 120 YEARS
THEIR AVERAGE AGE AT THE TIME OF THE BIRTH OF THE YOUNGEST MEMBER = [120 – (4 * 10)] / 4 = 30 – 10 = 20 YEARS
Answer: Option C. -> 25
LET THE NUMBER OF STUDENTS WHO WROTE THE EXAM BE X.
TOTAL MARKS OF STUDENTS = 80 X.
TOTAL MARKS OF (X – 5) STUDENTS = 90(X – 5)
80X – (5 * 40) = 90(X – 5)
250 = 10X => X = 25
LET THE NUMBER OF STUDENTS WHO WROTE THE EXAM BE X.
TOTAL MARKS OF STUDENTS = 80 X.
TOTAL MARKS OF (X – 5) STUDENTS = 90(X – 5)
80X – (5 * 40) = 90(X – 5)
250 = 10X => X = 25
Answer: Option A. -> 384
AVERAGE MARK SCORED BY ALL THE THREE BOYS =
[64/100 (800) + 36/100 (800) + 44/100 (800)] / 3 = 384
AVERAGE MARK SCORED BY ALL THE THREE BOYS =
[64/100 (800) + 36/100 (800) + 44/100 (800)] / 3 = 384
Answer: Option B. -> 86
LET THE FOUR INTEGERS BE A, B, C AND D WHERE A > B > C > D.
(A + B + C + D)/4 = 69 => A + B + C + D = 276 —> (1)
A = 93, D = 39 AND B – C = 28
(1) => B + C = 276 – (A + D) = 276 – 132 = 144.
B + B -28 = 144
B = (144 + 28)/2 = 86
LET THE FOUR INTEGERS BE A, B, C AND D WHERE A > B > C > D.
(A + B + C + D)/4 = 69 => A + B + C + D = 276 —> (1)
A = 93, D = 39 AND B – C = 28
(1) => B + C = 276 – (A + D) = 276 – 132 = 144.
B + B -28 = 144
B = (144 + 28)/2 = 86
Answer: Option D. -> 80
GIVEN M + P + C = 80 * 3 = 240 — (1)
M + P = 90 * 2 = 180 — (2)
P + C = 70 * 2 = 140 — (3)
WHERE M, P AND C ARE MARKS OBTAINED BY THE STUDENT IN MATHEMATICS, PHYSICS AND CHEMISTRY.
P = (2) + (3) – (1) = 180 + 140 – 240 = 80
GIVEN M + P + C = 80 * 3 = 240 — (1)
M + P = 90 * 2 = 180 — (2)
P + C = 70 * 2 = 140 — (3)
WHERE M, P AND C ARE MARKS OBTAINED BY THE STUDENT IN MATHEMATICS, PHYSICS AND CHEMISTRY.
P = (2) + (3) – (1) = 180 + 140 – 240 = 80
Question 3708. The average height of 35 boys in a class was calculated as 180cm. It has later found that the height of one of the boys in the class was wrongly written as 166 cm whereas his actual height was 106 cm. Find the actual average height of the boys in the class (Round off your answer to two decimal places)?
Answer: Option B. -> 178.29 cm
CALCULATED AVERAGE HEIGHT OF 35 BOYS = 180 CM.
WRONG TOTAL HEIGHT OF 35 BOYS = 180 * 35 CM. THIS WAS AS A RESULT OF AN ACTUAL HEIGHT OF 106 CM BEING WRONGLY WRITTEN AS 166 CM. CORRECT TOTAL HEIGHT OF 35 BOYS = 180 * 35 CM – 166 CM + 106 CM
= 180 * 35 CM – 166 CM + 106 CM/35 = 180 CM – 60 /35 CM
= 180 CM – 1.71 CM = 178.29 CM
CALCULATED AVERAGE HEIGHT OF 35 BOYS = 180 CM.
WRONG TOTAL HEIGHT OF 35 BOYS = 180 * 35 CM. THIS WAS AS A RESULT OF AN ACTUAL HEIGHT OF 106 CM BEING WRONGLY WRITTEN AS 166 CM. CORRECT TOTAL HEIGHT OF 35 BOYS = 180 * 35 CM – 166 CM + 106 CM
= 180 * 35 CM – 166 CM + 106 CM/35 = 180 CM – 60 /35 CM
= 180 CM – 1.71 CM = 178.29 CM
Answer: Option A. -> 4
LET THE NUMBER OFF BOYS IN THE GROUP ORIGINALLY BE X.
TOTAL WEIGHT OF THE BOYS = 30X
AFTER THE BOY WEIGHING 35 KG JOINS THE GROUP, TOTAL WEIGHT OF BOYS = 30X + 35
SO 30X + 35 + 31(X + 1) = > X = 4
LET THE NUMBER OFF BOYS IN THE GROUP ORIGINALLY BE X.
TOTAL WEIGHT OF THE BOYS = 30X
AFTER THE BOY WEIGHING 35 KG JOINS THE GROUP, TOTAL WEIGHT OF BOYS = 30X + 35
SO 30X + 35 + 31(X + 1) = > X = 4
Answer: Option B. -> 31 years
TOTAL AGE SEVEN PERSONS = (28 * 7)YEARS
TOTAL AGE OF THE FIRST THREE PERSONS AND THE LAST THREE PERSONS ARE (21 * 3) YEARS AND (34 * 3) YEARS RESPECTIVELY.
AGE OF THE PERSON SITTING IN THE MIDDLE OF THE ROW = 28 * 7 – 21 * 3 – 34 * 3 = 196 – 63 – 102 = 31 YEARS
TOTAL AGE SEVEN PERSONS = (28 * 7)YEARS
TOTAL AGE OF THE FIRST THREE PERSONS AND THE LAST THREE PERSONS ARE (21 * 3) YEARS AND (34 * 3) YEARS RESPECTIVELY.
AGE OF THE PERSON SITTING IN THE MIDDLE OF THE ROW = 28 * 7 – 21 * 3 – 34 * 3 = 196 – 63 – 102 = 31 YEARS
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