Average (1)

1. The average age of 40 boys in a class is 15. The average age of a group of 18 boys in the class is 16 and the average age of another12 boys in the class is 14. What is the average age of the remaining boys in the class?1.15.25 years
2. 14.4 years
3. 14.75 years
4. None of these
5. cannot be determined

Answer & Explanation

Answer:- 2

Explanation :-

Total students = 40 × 15 = 600
So, 18 x 16 + (12 + 14) = 456
Left student is 10 and their average is  = 600 – 456 = 144 ÷ 10 = 14.4

 

2. In Arun’s opinion, his weight is greater than 65 kg but less than 72 kg. His brother doest not agree with Arun and he thinks that Arun’s weight is greater than 60 kg but less than 70 kg. His mother’s view is that his weight cannot be greater than 68 kg. If all are them are correct in their estimation, what is the average of different probable weights of Arun?
1. 67 kg.
2. 68 kg.
3. 69 kg.
4. Data inadequate

Answer & Explanation

Answer:- 1

Explanation :-

Let Arun’s weight by x kg.
According to Arun, 65 < x < 72
According to Arun’s brother, 60 < x < 70.
According to Arun’s mother, x <= 68
The values satisfying all the above conditions are 66, 67 and 68.

 

3. The average marks of a student in eight subjects is 87. After revaluation in two subjects the marks were changed to 138 from 98 and 132 from 108. In remaining subjects the marks remained unchanged. What are the new average marks?
1. 97
2. 92
3. 98
4. 94
5. 95

Answer & Explanation

Answer:- 5

Explanation :-

Total marks = 87*8 = 696
previous marks of two subjects = 98 + 108 = 206
marks after revaluation = 138 + 132 = 270
Increased marks  =  270 – 206 = 64
Average after revaluation = (696 + 64)/ 8 = 95

 

4. The average score of Rahul, Manish and Suresh is 63. Rahul’s score is 15 less than Ajay and 10 more than Manish. If Ajay scored 30 marks more than the average score of Rahul, Manish and Suresh, what is the sum of Manish’s and Suresh’s score?
1. 120
2. 111
3. 117
4. Cannot be determined
5. None of these

Answer & Explanation

Answer:- 2

Explanation :-

Total Marks of Rahul, Manish and Suresh = 63*3 = 189
Ajay’s score = 63 + 30 = 93, Therefore
Rahul’s Score = 93 -15 = 78
Manish’s score = 78 – 10 = 68
Suresh’s score = 189 – (78 + 68) = 43
The sum of Manish’s and Suresh’s score = 43 + 68 = 111

 

5. The average age of 40 students of a class is 18 years. When 20 new students are admitted to the same class, the average age of students of class is increased by 6 m-onths. The average age of newly admitted students are?
1. 19 years
2. 19 years 6 months
3. 20 years
4. 20 years 6 months
5. None of these

Answer & Explanation

Answer:- 2

Explanation :-

Average age of 40 students = 18 years
Total age of 40 students = 40 * 18 = 720
Average age of 60 students = 18.5 * 60 = 1110 years
Average Age of 20 students = (1110 -720 )/20 = 390/20 = 19.5
Therefore Average age of newly admitted studens = 19 years 6 months

 

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