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Aptitude - Averages Online Quiz
Following quiz provides Multiple Choice Questions (MCQs) related to Averages. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.
Q 1 - If in a class room r boys is the average age in a year. What should be the average of remaining boys if b is the average age of s boys out of them?
Answer : A
Explanation
r boys have the sum of the age = (ra ) years. s boys have the sum of the age = (sb) years. (r-s) boys have the sum of the ages = (ra-sb) (r-s) boys have the average of the ages = (ra-sb)/ (r-s).
Q 2 - 28 is the average of 3 numbers. Find out the value of third number if the given condition is such that the second number have the double value in the comparison of first number and third number have 4 times value of first number?
Answer : A
Explanation
If x is the value of third number. Then the value of second number is x/2 , if x/2 is the value of second number then the value of first number will be 1/2 . x/2 = x/4. Total sum of three number = (3*28) =84 ∴ x+x/2+x/4 = 84 ⇒ 7x/4 = 84 ⇒ x= (84*4)/7 = 48 So, its proves that the value of the third number is 48.
Q 3 - 38.6°C is the average temperature of 4 first day of the week while 40.3°C is the average of last 4 days in a week. Find out the temperature on Thursday if 39.1°C is average of whole week?
Answer : C
Explanation
M+T+W+Th = (38.6*4)= 154.4 ...(i) T+W+Th+F = (40.3*4) =161.2 ...(ii) M+T+W+Th+F+S+Su =(39.1*7) =273.7 ...(iii) (i)+(ii) (iii) we find that , (154.4+161.2- 272.7) =41.9°C ∴ 41.9 °C was the temperature on Thursday.
Q 4 - Before the period of 10 years, 24years is the average of 4 members family. After two children born, the average age of the family no change if 2 years is the age difference between 2 children then what should be the youngest child age?
Answer : A
Explanation
x is the age of the youngest child. Then, elder son child age = (x+2) years. At the present day average age of 6 members = 24 years. At the present day , some of the ages of 6 members = (24*6)= 144 years. (24*4)+(10*4) +x+(x+2) =144 ⇒ 2x = 6 ⇒ x= 3 At the present time the youngest child have 3 year age old.
Q 5 - What should be the largest number if first number is the half of the second number and third number is 1/3 of the second number? 44 is the average of three numbers?
Answer : A
Explanation
if x is the third number , then second number = 3x ∴ first number = 3x/2 Average =1/3 (3x/2+3x+x) ⇒ (11x/6) =44 ⇒ 11x=264 ⇒ x = 24 Hence, the second number (24*3)=72 is the largest number.
Q 6 - 105 cm is the average height of 10 students. Find out the new average height if 20 students also join the class whose average height is 120 cm.
Answer : A
Explanation
10 student have total value of heights = (105* 10)= 1050 cm. 20 students have total value of heights = (120*20) = 2400 cm 30 students have total value of heights = (1050+2400) = 3450 cm. Average required = 3450/30 = 115 cm
Q 7 - 16 children are to be divided into two groups A and B of 10 and 6 children. The average percent marks obtained by the children of group A is 75 and the average percent marks of all the 16 children is 76. What is the average percent marks of children of group B?
Answer - A
Explanation
Required average = (76 x 16) - (75 x 10)⁄6 = 1216 - 750⁄6 = 466⁄6 233⁄3 = 772⁄3
Q 8 - Of the three numbers, the average of the first and the second is greater than the average of the second and the third by 15. What is the difference between the first and the third of the three numbers?
Answer - A
Explanation
Let the numbers be a, b, and c. Then, (a + b)⁄2 - (b + c)⁄2 = 15 or or (a + b) - (b + c) = 30 or a - c = 30
Q 9 - The average weight of a class of 24 students is 35 kg. If the weight of the teacher be included, the average rises by 400g. The weight of the teacher is:?
Answer - B
Explanation
Weight of the teacher = (35.4 x 25 - 35 x 24)kg = 45 kg
Q 10 - 3 years ago. the average age of a family of 5 members was 17 years. A baby having been born, the average age of the family is the same today. The present age of the baby is ?
Answer - C
Explanation
Total age of 5 members, 3 years ago = (17 x 5) years = 85 years Total age of 5 members now = (85 + 3 x 5) yrs = 100 years Total age of 6 members now = (17 x 6) years = 102 years Therefore Age of younger child = (102 - 100) = 2 years