Average problems
- 1. Average monthly income of a family of 4 earning members was Rs. 735. One of the earning members died and therefore, the average income came down to Rs 650. The income of the deceased was?
Options- A. Rs. 692.80
- B. Rs. 820
- C. Rs. 990
- D. Rs. 1385 Discuss
Correct Answer: Rs. 990
Explanation:
Income of the deceased = Total income of 4 members - total income of remaining 3 members.
= 735 x 4 - 650 x 3 Rs.
= 990 Rs.
- 2. The average age of 24 students in a class is 10. If the teacher's age is included, the average increase by one . The age of the teacher is?
Options- A. 25 year
- B. 30 year
- C. 35 year
- D. 40 year Discuss
Correct Answer: 35 year
Explanation:
Age of the teacher = Sum of age of 24 students and teacher - Sum of age of 24 students.
= 25 x 11 - 24 x 10
= 35 years.
? Age of teacher = 35 years.
- 3. The average expenditure of a man for the first five month is Rs. 120 and for the next seven months it is Rs . 130. if he saves Rs 299 in that year, his monthly average income is?
Options- A. Rs. 140
- B. Rs. 150
- C. Rs. 160
- D. Rs. 170 Discuss
Correct Answer: Rs. 150
Explanation:
Total income = total expenditure + total saving
= Rs. (120 X 5 + 130 X 7 + 290)
=Rs. 1800
Average monthly income
=1800 / 12
=150 Rs.
- 4. The average salary of 20 workers in an office id Rs. 1900 per month . If the manger's salary is added , the average salary become Rs. 2000 p.m what is the manager's annual salary?
Options- A. Rs. 24000
- B. Rs. 25200
- C. Rs. 45600
- D. None of these Discuss
Correct Answer: None of these
Explanation:
Manager's salary per month
= Rs. ( 21 x 2000 - 20 x 1900 )
= Rs. 4000
? Manager 's annual salary
= Rs. (4000 X 12 ) = Rs. 48000.
- 5. The average of 6 observation is 12. A new 7th observation is included and the new average is decrease by 1 , the seventh observation is?
Options- A. 1
- B. 3
- C. 5
- D. 6 Discuss
Correct Answer: 5
Explanation:
Seventh observation = sum of 7 observations - sum of 6 observations = 7 x 11 ? 6 x 12
= 5
- 6. Out of four number, the average of first three is 15 and that of the last three is 16, if the last number is 19, the first is?
Options- A. 15
- B. 16
- C. 18
- D. 19 Discuss
Correct Answer: 16
Explanation:
Sum of four number = ( 15 x 3 + 19 ) = 64
Sum of last three number = ( 16 x 3 ) = 48
? first number = ( 64 ? 48 ) = 16
- 7. The average temperature of the first three days is 27° C and that of the next three is 29° C . If the average of the whole week is 28.5° C, the temperature of the last day of the week is?
Options- A. 10.5° C
- B. 21° C
- C. 31.5° C
- D. 42° C Discuss
Correct Answer: 31.5° C
Explanation:
Temperature of last day = Sum of temperature of 7 days - sum of temperature of first 6 days.
= ( 7 x 28.5 ) - [( 3 x 27 ) + ( 3 x 29 )]
=31.5
? Temperature of last day = 31.5
- 8. A ship sails out to a mark at the rate of 15 kmph. and sails back at the rate of 10 kmph. The average rate of sailing is?
Options- A. 5 km/hr
- B. 12 km/hr
- C. 12.5 km/hr
- D. 25 km/hr Discuss
Correct Answer: 12 km/hr
Explanation:
Average = ( 2uv / u +v ) km/hr
= ( 2 x 15 x 10 ) / (15 +10 ) km/hr.
= 12 km/hr.
- 9. The average consumption of petrol for a car for seven months is 110 litres and for next five months it is 86 litres. The average monthly consumption is?
Options- A. 96 litres
- B. 98 litres
- C. 100 litres
- D. 102 litres Discuss
Correct Answer: 100 litres
Explanation:
Average = ( sum of consumption of petrol in first 7 months + sum of consumption of petrol in last 5 months. ) / 12
Average = ( 110 x 7 + 86 x 5 ) / 12
=(1200 / 12 = 100 liters
- 10. A batsman has a certain average runs for 11 innings . In the 12th innings he made a score of 90 runs and thereby decrease his average by 5 . His average after 12th innings is?
Options- A. 127
- B. 145
- C. 150
- D. 217 Discuss
Correct Answer: 145
Explanation:
Let the average for first 11 innings is y
From question
11y + 90 = (y - 5) x 12
? y = 150
? Average after 12th inning = (150 - 5)= 145
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