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- Question
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
- Correct Answer
- 81.5
ExplanationLet 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 - 1. Aarti can do a piece of work in 6 days. In how many days will she complete three time of work of same type?
Options- A. 18 days
- B. 21 days
- C. 3 days
- D. 6 days Discuss
- 2. 750.0003 ÷ 19.999 =?
Options- A. 49
- B. 18
- C. 22
- D. 38 Discuss
- 3. 105, 85, 60, 30, 0, - 45, - 90?
Options- A. 0
- B. 85
- C. -45
- D. 60 Discuss
- 4. Let A = {1, 2, {3, 4}, 5}. Which of the following statements is true?
Options- A. {3, 4} ? A
- B. {3, 4} ? A
- C. 1 ? A
- D. {1, 2, 5} ? A Discuss
- 5. Two vessels A and B contains milk and water mixed in the ratio 5 : 3 and 2 : 3. When these mixtures are mixed to form a new mixture containing half milk and half water, they must be taken in the ratio ?
Options- A. 2 : 5
- B. 3 : 5
- C. 4 : 5
- D. 7 : 3 Discuss
- 6. 1, 2, 4, 8, 16, 32, 64, (...), 256?
Options- A. 148
- B. 128
- C. 154
- D. 164 Discuss
- 7. A tree is 12 m tall and casts an an 8 m long shadow. At the same time, a flag pole caste a 100 m long shadow. How long is the flag pole?
Options- A. 150 m
- B. 200 m
- C. 125 m
- D. 115 m Discuss
- 8. 8% of 96 =? of 1/25
Options- A. 19.2
- B. 7.68
- C. 1.92
- D. None of these Discuss
- 9. A certain amount earns simple interest of Rs. 1750 after 7 years. Had the interest been 2% more, how much more interest would it have earned?
Options- A. Rs. 35
- B. Rs. 245
- C. Rs. 350
- D. Cannot be determined
- E. None of these Discuss
- 10. If the hands of a clock coincide in every 65 minutes (true time), in 24 hours the clock will gain:
Options- A. 10 10 minutes. 143
- B. 9 12 minutes. 143
- C. 11 12 minutes. 143
- D. 12 10 minutes. 143 Discuss
More questions
Correct Answer: 18 days
Explanation:
We have the important relation, More work, More time (days)
? A piece of work can be done in 6 days.
? Three times of work of same type can be done in 6 x 3
= 18 days
Correct Answer: 38
Explanation:
? = 750.0003 ÷ 19.999
? ? ? 750 ÷ 20
? ? ? 375 ? 38
Correct Answer: 0
Explanation:
Subtract 20, 25, 30, 35, 40, 45 from successive numbers. So 0 is wrong.
Correct Answer: {3, 4} ? A
Explanation:
NA
Correct Answer: 4 : 5
Explanation:
Correct Answer: 128
Explanation:
Each previous number is multiplied by 2.
Correct Answer: 150 m
Explanation:
? 8 m shadow means original height = 12 m
? 1 m shadow means original height = 12/8 m
? 100 m shadow means original height = (12/8) x 100 m
= (6/4) x 100 = 6 x 25 = 150 m
Correct Answer: None of these
Explanation:
Let 8% of 96 = y of 1/25
? (8 x 96)/100 = y/25
? y = (8 x 96 x 25)/100 = 192
Correct Answer: Cannot be determined
Explanation:
We need to know the S.I., principal and time to find the rate.
Since the principal is not given, so data is inadequate.
Correct Answer: 10 10 minutes. 143
Explanation:
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