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- Question
- If 2n + 1P n - 1 : 2n - 1P n = 3 : 5, then n is equal to?
Options- A. 4
- B. 6
- C. 3
- D. 8
- Correct Answer
- 4
ExplanationWe have If 2n + 1Pn - 1 / 2n - 1Pn = 3/5
? 5 x 2n + 1Pn - 1 = 3 x 2n - 1Pn
? {5 x (2n + 1)!} / {(n + 2 )!} = 3 x {(2n - 1)!} / {(n - 1)!}
? 10(2n + 1) = 3(n + 2) (n + 1)
? 3n2 - 11n - 4 = 0
?(3n + 1 ) (n - 4) = 0
? n = 4 - 1. What is the average of four tenths and five thousandths
Options- A. 25002
- B. 2502
- C. 0.2025
- D. none Discuss
- 2. Which number will come in place of question mark 7, 16, 36, 78, 144, ?
Options- A. 168
- B. 196
- C. 222
- D. 256 Discuss
- 3. Seven years ago, the average age of A, B and C was 51 years. If A is 3 years older than B and B is 3 years older then C then the present ages of A, B and C are ( in year)
Options- A. 61, 58 and 55
- B. 54, 51, and 48
- C. 55, 58, and 61
- D. 48, 51 and 54 Discuss
- 4. In the given figure, PQRS is a square inscribed in a circle of radius 4 cm. PQ is produced till point Y. From Y a tangent is drawn to the circle at point R. What is the length (in cm) of SY ?
Options- A. 4√10
- B. 2√10
- C. 6√10
- D. 3√5 Discuss
- 5. If V = 12R / (r + R) , then R =
Options- A. Vr / (12 - V)
- B. Vr + (V /12 )
- C. V
- D. V / (r - 12 ) Discuss
- 6. In a class of 60 students there are 20 girls who scored an average of 40 marks in the test, what is the average marks of the boys if the class average is 60 marks?
Options- A. 60
- B. 70
- C. 50
- D. D) Discuss
- 7. Which of the fractions given below, when added to 5/8, gives 1?
Options- A. 6/16
- B. 5/2
- C. 6/24
- D. 6/3 Discuss
- 8. LCM of 80, 85, 90
Options- A. 11440
- B. 11998
- C. 12240
- D. 12880 Discuss
- 9. In a triangle, the distance of the centroid from the three vertices is 4cm, 6cm and 8cm respectively. Then the length of the smallest median is:
Options- A. 8
- B. 7
- C. 6
- D. 5 Discuss
- 10. In a mixture of 25 litres, the ratio of milk to water is 4:1. Another 3 litres of water is added to the mixture. The ratio of milk to water in the new mixture is
Options- A. 5:1
- B. 5:2
- C. 5:3
- D. 5:4 Discuss
More questions
Correct Answer: 0.2025
Explanation:
Four tenths = 0.4
Five thousandths = 0.005
The average is (0.4 + 0.005)/2 = 0.2025
Correct Answer: 222
Correct Answer: 61, 58 and 55
Correct Answer: 4√10
Correct Answer: Vr / (12 - V)
Explanation:
We have to rearrange the equation to make R the subject.
Start by cross multiplying by (r + R); V (r + R) = 12R
Multiply out the bracket Vr + VR = 12R
Correct Answer: 70
Correct Answer: 6/16
Correct Answer: 12240
Explanation:
LCM of (80, 85, 90) can be found by prime factorizing them.
80 ? 2 × 2 × 2 × 2 × 5
85 ? 17 × 5
90 ? 2 × 3 × 3 × 5
L.C.M of (80,85,90) = 2 × 2 x 2 × 2 × 3 × 3 × 5 × 17
= 16 x 9 x 85
= 144 x 85
= 12240
L.C.M of (80,85,90) = 12240.
Correct Answer: 6
Correct Answer: 5:2
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