Average problems
- 1. A man divides his total route of journey into three equal parts and decide to travel the three parts with speed of 15 km/h. 10 km/h and 5 km/ h respectively. Find his average speed of during journey.
Options- A. 2.28 km/h
- B. 9 km/h
- C. 14 km/h
- D. 8.18 km /h Discuss
Correct Answer: 8.18 km /h
Explanation:
If three equal distances are covered at different spees of A, B and C km/h, respectively, then average speed during whole journey
= 3ABC/(AB + BC + CA) km/h
? Required average speed
= (3 x 15 x 10 x 5) / (15 x 10 + 10 x 5 + 15 x 5)
= (3 x 15 x 10 x 5)/(150 + 50 + 75)
= (3 x 15 x 10 x 5)/275
= 8.18 km/h
- 2. The average temperature of Delhi for four days in a particular month is 48°C. If the average temperature of second and third days 34°C and the ratio of the temperature of first and fourth days is 9 : 11 then find out the temperature of first and fourth days.
Options- A. 45.5°C, 49.9°C
- B. 32.4°C, 39.8°C
- C. 43.4°C, 68.2°C
- D. 54.4°C, 46.8°C Discuss
Correct Answer:
Explanation:
Total temperature of first and fourth days= (4 x 48 - 2 x 34)°C
= (192 - 68)°C= 124°C
Now, according to the question
Temperature of the first day = (9/20) x 124 = 55.8°C
Temperature of fourth day = (11/20) x 124 = 68.2°C
- 3. A man spends average of ? 1694. 70 per month for the first 7 month and ? 1810.50 per month for the next 5 months. His monthly salary if he saves ? 3084.60. during the whole year is?
Options- A. ? 2400
- B. ? 3000
- C. ? 1000
- D. ? 2000 Discuss
Correct Answer: ? 2000
Explanation:
Let the monthly salary of a man = ? N
? The annual salary = ? 12N
According to the question,
Annually spends of a man = 7 x 1694.70 + 5 x 1810.50
= ? 20915.40
? His monthly spends = 20915.40/12 = ? 1742.95
And monthly saving = 3084.60/12 = ? 257.05
? His monthly salary
= 1742.95 + 257.05
= ? 2000
- 4. In the afternoon, a student read 100 pages at the rate of 60 pages/h. In the evening, when she was tired, she read 100 more pages at the rate of 40 pages/h . What was her average rate of reading in pages per hour?
Options- A. 48
- B. 50
- C. 60
- D. 70 Discuss
Correct Answer: 48
Explanation:
Required average rate of reading
= 2AB / (A + B) = 2 x 60 x 40 / (60 + 40)
= (2 x 60 x 40)/100 = 48 page/h
- 5. Mr. Bundda travels in this car and covers 1/4 part of his journey with 8 km/h, 3/5 part with 6 km/h and remaining 3/20 part with a speed of 10 km/h. Find out his average speed during the whole journey.
Options- A. 6.83 km/h
- B. 9 km/h
- C. 4 k/h
- D. 8.5 km/h Discuss
Correct Answer: 6.83 km/h
Explanation:
According to the average speed formula,
P = 1/4, Q =3/5, R = 3/20
x = 8 km/h, y = 6 km/h, z = 10km/h
? Required average speed = 1 / [(P/x) + (Q/y) + (R/z)]
=1 / [(1/32) + (1/10) + (3/200)]
= 1/[(25 + 80 + 12)/800]
= 800/117
= 6.83 km/h
- 6. A person covers 9 km with a speed of 3 km/h, 25 km with a speed of 5 km/h and 30 km with a speed of 10 km/h. Find out the average speed of person.
Options- A. 59/11 km/h
- B. 115/9 km/h
- C. 95/11 km/h
- D. 55/11 km/h Discuss
Correct Answer: 59/11 km/h
Explanation:
Here, P = 9 km/h, Q = 25 km/h, R = 30 km
x = 3 km/h, y = 5 km/h and z = 10 km/h
? Required average speed
= [P + Q + R] / [(P/x) + (Q/y) + (R/z)] = [9+25 + 30] / [(9/3) + (25/5) + (30/10)]
= 64/(3 + 5 + 3)
= 64/11
= 59/11 km/h
- 7. The daily minimum temperature of a place in a certain week. begining from Monday was 20°, 18.6°, 17°, 21.4°, 19° and 19.8°. It was known that the average of whole week was 19.5°. The minimum temperature on Sunday was?
Options- A. 16.9°
- B. 11.6°
- C. 20.7°
- D. 12.6° Discuss
Correct Answer: 20.7°
Explanation:
Let temperature on sunday be x° C.
(20° + 18.6° + 17° + 21.4° + 19° + 19.8° + x) / 7 = 19.5°
? 115.8 + x = 19.5 x 7
? x = 136.5 - 11.58
? x = 20.7°C
- 8. Average weight of three boys P, T and R is 54 1/ 3 kg, while the average weight of three boys T, F and G is 53 kg. What is the average weight of P, T, R, F and G?
Options- A. 53.8 kg
- B. 52.4 kg
- C. 53.4 kg
- D. Cannot be determined Discuss
Correct Answer: Cannot be determined
Explanation:
According to the question
(P + T + R) / 3 = 541/3
? P + T + R = (163/3) x 3
? P + T + R = 163 ............(i)
Also (T + F + G)/3 = 53
? T + G + F = 159 ..........(ii)
Clearly, from the two Eqs. (i) and (ii), the problem cannot be solved.
- 9. The average runs scored by a cricketer is 42 innings, is 30. The difference between his maximum and minimum scores in an inning is 100. If these two innings are not taken into consideration, then the average score of remaining 40 inning is 28. Calculate the maximum runs scored by him in an innings?
Options- A. 125
- B. 120
- C. 110
- D. 100 Discuss
Correct Answer: 120
Explanation:
Let the minimum score = x
? Maximum score = x + 100
? x + (x + 100) = 30 x 42 - 40 x 28
? 2x + 100 = 1260 - 1120 = 140
? 2x = 140 - 100 = 40
? x = 20
Hence, the maximum score = x + 100
= 20 + 100 = 120
- 10. A car reached Raipur from Somgarh in 35 min With an average speed of 69 km/h. If the average speed is increased by 36 km/h, how much time will it take to cover the same distance?
Options- A. 24 min
- B. 27 min
- C. 23 min
- D. 29 min Discuss
Correct Answer: 23 min
Explanation:
Distance between Raipur and Somgarh
= Average speed x Time
= 69 x 35/60= 161/4 km
New speed = (69 + 36) km/h = 105 km/h
? Time = Distance/ Speed = 161/4 x 105 h
= 161 x 60/4 x 105min = 23 min
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