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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 - What is the average of first 9 multiples of 3?

Answer : A

Explanation

Average = (3+6+9+12+15+18+21+24+27)/ 9= 135/9 = 15

Q 2 - 23 is the average of 3 friends if we add 1 more person then the value of average will be same or no change. Find out the age of the new person?

Answer : D

Explanation

3 friends have the sum of the ages = (3*23)= 69 ...(i)
4 friend have the sum of the ages = (4*23)=92 ...(ii)
Difference between  the (i) and (ii)  is the age of the new person.  We find that the age of the  new person is (92-69)= 23 years.

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 - 18 year was the average age of A and B before the period of 3year. The average age increased by 4 year after joining C. What should be the age of C at the present time?

Answer : A

Explanation

Before the period of 3 year, sum of the ages of A and B = (18*2)= 36 years.
At the present time, sum of the ages of A and B = (36+3*2) =42 years.
Sum of the ages of A, B and C = (22*3) = 66 years.
∴  C age at the present time = (66-42)= 24 years.

Q 5 - N is average of 5 consecutive natural numbers if we add 2 upcoming numbers then what should be the seven number averages?

Answer : A

Explanation

x, x+1, x+2, x+3 and x+4 is the 5 natural consecutive numbers.  Then ,
x+(x+1)+(x+2)+(x+3)+(x+4)= 5n ⇒ 5x+10=5n ⇒ x = 5(n-2)/5 = (n-2)
∴  7 consecutive natural numbers are  (n-2),(n-1), n,(n+1), (n+2),(n+3)
Average of 7 consecutive natural numbers =( 7n+1/7 ) = (n+1)  ∴ average increase by 1.

Q 6 - Find out the original average weight of the class if 1 kg weight increased in average weight if we add a new person who has 50 kg. If one more add in the class then the average weight increased with 1.5 kg over the original average.

Answer : A

Explanation

if x is the average the number of students and y is the average weight.
Then ,   xy+50/ (x+1) =(y+1) ⇒ xy+50=  xy+x+y+1 ⇒ x+y= 49...(i)
xy+50+50/(x+2) = (y+3/2 )⇒ xy+100 = xy +3x/2+2y+3
⇒  3x/2+ 2y = 97 ⇒ 3x+4y =194 ...(ii)
Multiplying (i) by 3 and subtracting it from (iii), we get y =47.
Hence , the original average of weight is 47 kg.

Q 7 - The average of six numbers is 3.95. The average of two of them is 3.4, while the average of the other two is 3.85. What is the average of the remaining two numbers?

Answer - B

Explanation

Sum of the remaining two numbers = (3.95 x 6) - [(3.4 x 2) + (3.85 x 2)] = 23.70 - (6.8 + 7.7) = 23.70 - 14.5 = 9.20 
Therefore Required average = ^9.2⁄₂ = 4.6.

Q 8 - The average temperature of the town in the first four days of a month was 58 degrees. The average for the second, third, fourth and fifth days was 60 degrees. If the temperatures of the first and fifth days were in the ratio 7:8, then what is the temperature on the fifth day?

Answer - A

Explanation

Sum of temperature on 1st, 2nd, 3rd and 4th days = (58 x 4) = 232 degrees ...(i) 
Sum of temperature on 2nd , 3rd 4th and 5th days = (60 x 4) = 240 degrees ...(ii) 
Subtracting (i) from (ii) we get: 
Temp on 5th day - temp on 1st day = 8 degrees 
Let the temperature on 1st and 5th days be 7z and 8z degrees respectively. 

Then, 8z - 7z = 8 or z = 8. 
Therefore Temperature on 5th day = 8z = 64 degrees.

Q 9 The average weight of 8 persons increases by 2.5kg when a new person comes in place of one of them weighing 65kg . what might be the weight of the new person?

Answer - A

Explanation

Total weight increased = (8 x 2.5) kg = 20kg 
Weight of new person = (65 + 20) kg = 85kg.

Q 10 - The average age of husband, wife and their child 3 years ago was 27 years and that of wife and the child 5 years ago was 20 years. The present age of the husband is?

Answer - A

Explanation

Sum of the present ages of husband, wife and child = (27 x 3 + 3 x 3) years = 90 years. 
Sum of the present ages of wife and child = (20 x 2 + 5 x 2) years = 50 years 
Therefore Husbands present age = (90 - 50) years = 40 years

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