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- Question
After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. The difference between the ages of the replaced and the new members?
Options- A. 16 years
- B. 15 years
- C. 14 years
- D. 13 years
- Correct Answer
- 15 years
ExplanationLet avg ages of 5 members at present is G
And age of new member is m and an older is n
Required = (5G + m - n)/5 = G - 3
m - n = 15 years
- 1. A motorist travels to a place 150 km away at an average speed of 50 km/hr and returns at 30 km/hr. His average speed for the whole journey in km/hr is :
Options- A. 35
- B. 36
- C. 37.5
- D. 38.2 Discuss
- 2. The average age of a group of persons going for picnic is 16 years. Twenty new persons with an average age of 15 years join the group on the spot due to which their average age becomes 15.5 years. The number of persons initially going for picnic is :
Options- A. 15
- B. 20
- C. 23
- D. 24 Discuss
- 3. Out of three numbers, the first is twice the second and is half of the third. If the average of the three numbers is 56, what will be the sum of the highest number and the lowest number?
Options- A. 120
- B. 160
- C. 80
- D. 60 Discuss
- 4. The ratio of speeds of a car, a train and a bus is 5:9:4. The average speed of the car, the bus and the train is 72 km/hr together. What is the average speed of the car and the train together ?
Options- A. 84 km/hr
- B. 96 km/hr
- C. 72 km/hr
- D. 60 km/hr Discuss
- 5. The average age of 15 students of a class is 15 years. Out of these, the average age of 5 students is 14 years and that of the other 9 students is 16 years, The age of the 15th student is :
Options- A. 11
- B. 12
- C. 13
- D. 14 Discuss
- 6. The average monthly salary of 20 employees in an organisation is Rs. 1500. If the manager's salary is added, then the average salary increases by Rs. 100. What is the manager's monthly salary ?
Options- A. 3600
- B. 3700
- C. 3800
- D. 3900 Discuss
- 7. In a mixture of three varities of oils , the ratio of their weight is 4 : 5 : 8. If 5 kg of oils of the first variety, 10 kg of the second variety and some quantity of oils of the third variety are added to the mixture, the ratio of the weights of three varieties of oils becomes as 5 : 7 : 9 in the final mixture, find the quantity of third variety of oil was ?
Options- A. 15 kg
- B. 25 kg
- C. 35 kg
- D. 45 kg Discuss
- 8. What will be the cost of building a fence around a square plot with area equal to 289 sq ft, if the price per foot of building the fence is Rs. 58 ?
Options- A. Rs. 3748
- B. Rs. 3847
- C. Rs. 3944
- D. Rs. 3154 Discuss
- 9. It costs Rs. p each to send the first thousand messsages and Rs. q to send each subsequent one . If r is greater than 1,000, how many Rupees will it cost to send r messages ?
Options- A. 1000 (r - p) + pq
- B. 1000 p + qr
- C. 1000 (r - q) + pr
- D. 1000(p - q) + qr Discuss
- 10. Three maths classes: A, B and C take an algebra test. The average score of class A is 83. The average score of class B is 76. The average score of class C is 85. The average score of class A and B is 79 and average score of class B and C is 81. What is the average score of classes A, B, C ?
Options- A. 81
- B. 78
- C. 80.5
- D. 81.5 Discuss
Average problems
Search Results
Correct Answer: 37.5
Explanation:
Average speed = (2xy) /(x + y) km/hr
= (2 * 50 * 30) / (50 + 30) km/hr.
37.5 km/hr.
Correct Answer: 20
Explanation:
Let the initial number of persons be x. Then,
16x + 20 * 15 = 15.5 (x + 20) <=> 0.5x = 10 <=> x = 20.
Correct Answer: 120
Explanation:
Let the three numbers be x, y, z.
From the gien data,
x = 2y ....(1)
x = z/2 => z = 2(2y) = 4y .....(From 1) ...........(2)
Given average of three numbers = 56
Then,
Now,
x = 2y => x = 2 x 24 = 48
z = 4y = 4 x 24 = 96
Now, the highest number is z = 96 & smallest number is y = 24
Hence, required sum of highest number and smallest number
= z + y
= 96 + 24
= 120.
Correct Answer: 84 km/hr
Explanation:
Let the speeds of the car, train and bus be 5x, 9x and 4x km/hr respectively.
Average speed = 5x + 9x + 4x/3 = 18x /3 = 6x km/hr.
Also, 6x = 72 => x = 12 km/hr
Therefore, the average speed of the car and train together is =
= 7x = 7 x 12 = 84 km/hr.
Correct Answer: 11
Explanation:
Age of the 15th student = [15 * 15 - (14 * 5 + 16 * 9)] = (225-214) = 11 years.
Correct Answer: 3600
Explanation:
Manager's monthly salary Rs. (1600 * 21 - 1500 * 20) = Rs. 3600.
Correct Answer: 45 kg
Explanation:
Let the ratio of initial quantity of oils be 'x' => 4x, 5x & 8x.
Let k be the quantity of third variety of oil in the final mixture.
Let the ratio of initial quantity of oils be 'y'
From given details,
4x + 5 = 5y ..... (1)
5x + 10 = 7y .....(2)
8x + k = 9y ......(3)
By solving (1) & (2), we get
x = 5 & y = 5
From (3) => k = 5
Therefore, quantity of third variety of oil was 9y = 9(5) = 45kg.
Correct Answer: Rs. 3944
Explanation:
Let the side of the square plot be 'a' ft.
Given area of the plot (a x a) = 289 => a = 17
Length of the fence = Perimeter of the plot = 4a = 68 ft.
Cost of building the fence = 68 x 58 = Rs. 3944.
Correct Answer: 1000(p - q) + qr
Explanation:
We need to find the total cost to send r messsages, r > 1000.
The first 1000 messsages will cost Rs.p each (Or)
The total cost of first 1000 messsages = Rs.1000p
The remaining (r - 1000) messsages will cost Rs.q each (Or)
The cost of the (r - 1000) = Rs.(r - 1000)y
Therefore, total cost = 1000p + rq - 1000q
= 1000(p - q) + qr
Correct Answer: 81.5
Explanation:
Let the number of students in classes A, B and C be P, Q and R respectively.
Then, total score of A = 83P, total score of B = 76Q, total score of C = 85R.
Also given that,
(83P + 76Q) / (P + Q) = 79
=>4P = 3Q.
(76Q + 85R)/(Q + R) = 81
=>4R = 5Q,
=>Q = 4P/3 and R = 5P/3
Therefore, average score of A, B, C = ( 83P + 76Q + 85R ) / (P + Q + R) = 978/12 = 81.5
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