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- Question
- Mohan gets 3 marks for each correct sum and loses 2 marks for each wrong sum. He attempts 30 sums and obtains 40 marks. The number of sums solved correctly is
Options- A. 25
- B. 10
- C. 15
- D. 20
- Correct Answer
- 20
ExplanationSolution 1.
Let the question solved correctly by Mohan = X ;
and number of question solved wrongly by Mohan = 30 - X ;
According to the question,
3X - (30 - X) x 2 = 40
? 3x - 60 + 2x = 40
? 5x - 60 = 40
? 5x = 40 + 60 ? x = 100/5 = 20
? Mohan attempted 20 questions correctly .
Solution 2.
Let the question solved correctly by Mohan = X ;
and number of question solved wrongly by Mohan = Y ;
According to given question;
X + Y = 30 ; -----------i
3X - 2Y = 40 ;-------ii
Now multiply the first equation by 2;
we will get
2X + 2Y = 60 ;--------iii
After Add the equation ii and iii , we will get
3X - 2Y + 2X + 2Y = 40 + 60 ;
? 5X = 100 ;
? X = 20;
? Mohan attempted 20 questions correctly . - 1. A man buys 3 cows and 18 goats in ? 47,200. Instead if he would have bought 8 cows and 3 goats, he had to pay ? 53,000 more. Cost of one cow is:
Options- A. ? 10,000
- B. ? 11,000
- C. ? 12,000
- D. ? 13,000 Discuss
- 2. Six years ago, the ratio of the ages of Kunal and Sagar was 6 : 5. Four years hence, the ratio of their ages will be 11 : 10. What is Sagar's age at present?
Options- A. 16 years
- B. 18 years
- C. 20 years
- D. Cannot be determined
- E. None of these Discuss
- 3. (17.28 ÷? ) / (3.6 x 0.2) = 2
Options- A. 120
- B. 1.20
- C. 12
- D. 0.12 Discuss
- 4. If a, b and c are non-zero, a + (1/b) = 1 and b + (1/c) = 1, then the value of abc is
Options- A. -3
- B. 1
- C. -1
- D. 3 Discuss
- 5. A ladder 15 m long reaches a window which is 9 m above the ground on one side of street. Keeping its foot at the same point, the ladder is turned to the other side of the street to reach a window 12 m high. What is the width of the street:
Options- A. 31 m
- B. 12 m
- C. 30 m
- D. 21 m Discuss
- 6. 4, 2, 3.5, 7.5, 26.25, 118.125
Options- A. 118.125
- B. 26.25
- C. 3.5
- D. 2 Discuss
- 7. If the square of the sum of two numbers is equal to 4 times of their product. then the ratio of these numbers is:
Options- A. 2 : 1
- B. 1 : 3
- C. 1 : 1
- D. 1 : 2 Discuss
- 8. What is the area of a square having perimeter 68 cm?
Options- A. 361 sq cm
- B. 284 sq cm
- C. 269 sq cm
- D. 289 sq cm Discuss
- 9. A and B can do a job together in 7 days. A is 1¾ times as efficient as B. The same job can be done by A alone in :
Options- A.
9 1 days 3 - B. 11 days
- C.
12 1 days 4 - D.
16 1 days 3
Discuss
- 10. Area of a square is 1/2 hectare. The diagonal of the square is?
Options- A. 250 meter
- B. 100 meter
- C. 50? 2 meter
- D. 50 meter Discuss
More questions
Correct Answer: ? 12,000
Explanation:
Correct Answer: 16 years
Explanation:
| Then, | (6x + 6) + 4 | = | 11 |
| (5x + 6) + 4 | 10 |
⟹ 10(6x + 10) = 11(5x + 10)
⟹ 5x = 10
⟹ x = 2.
∴ Sagar's present age = (5x + 6) = 16 years.
Correct Answer: 12
Explanation:
Let (17.28 ÷ N ) / (3.6 x 0.2) = 2
Then, 17.28 / N = 1.44
? N = 17.28 / 1.44
= 12
Correct Answer: -1
Explanation:
? a + (1/b) = 1
ab + 1 = b ......(i)
Also, b + (1/c) = 1
? b = 1 - (1/c) ....(ii)
From Eqs. (i) and (ii), we get
ab + 1 = 1 - (1/c)
? ab = -1/c
? abc = -1
Correct Answer: 21 m
Explanation:
Draw a figure as per given question,
In a Right triangle ADC, Use the (Pythagoras Theorem)
AC = ?DC2 - AD2
? AC = ? 152 - 9 2
? AC = ? 225 - 81
? AC = ? 144
? AC = 12 cm
In a Right triangle BCE, Use the formula
CB = ? CD2 - BE2
? CB = ?15 2 - 122
? CB = ?225 - 144
? CB = ? 81
? CB = 9 m
? Width of the street (AC + BC) = AB = 12 + 9 = 21 m.
Correct Answer: 3.5
Explanation:
Series pattern 4 x 0.5 = 2
2 x 1.5 = 3
Should come in place of 3.5
3 x 2.5 = 7.5
7.5 x 3.5 = 26.25
26.25 x 4.5 = 118.125
Clearly, 3.5 is wrong and is replaced by 3.
Correct Answer: 1 : 1
Explanation:
Let the number be p and q.
According to question,
(p + q)2 = 4pq
? p2 + q2 + 2pq ? 4pq = 0
? (p ? q)2 = 0
? p = q
Hence , required ratio is 1 : 1 .
Correct Answer: 269 sq cm
Explanation:
According to the question,
4a = 68 [ where a = side]
?a = 68/4 = 17 cm
? Required area = a2
= (17)2 = 289 sq cm
Correct Answer: 11 days
Explanation:
| (A's 1 day's work) : (B's 1 day's work) = | 7 | : 1 = 7 : 4. |
| 4 |
Let A's and B's 1 day's work be 7x and 4x respectively.
| Then, 7x + 4x = | 1 | ⟹ 11x = | 1 | ⟹ x = | 1 | . |
| 7 | 7 | 77 |
| ∴ A's 1 day's work = | ❨ | 1 | x 7 | ❩ | = | 1 | . |
| 77 | 11 |
Correct Answer: 100 meter
Explanation:
Area = 1/2 hectare = 10000 / 2 m2
= 5000 m2
Again Area = 1/2 x (Diagonal)2
So 1/2 x (Diagonal)2 = 5000m2
? Diagonal2= 10000
? Diagonal = 100
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