Discussion
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- Question
- If the second term of an HP is 1/6 and the fourth terms is 1/14, then find the tenth term of the HP?
Options- A. 1/32
- B. 1/36
- C. 1/38
- D. 1/40
- Correct Answer
- 1/38
ExplanationThe second and fourth term of the HP are 1/6 and 1/14 respectively,
Hence, for the corresponding AP, the second term is 6 and fourth term is 14.
Hence a + d = 6 and a + 3d = 14
? 2d = 8
? d = 4 and a = 2
Hence, the 10th term of this AP = a + (10 -1)d
= 2 + (10 - 1)x 4 = 2 + 9 x 4
= 2 + 36 = 38
Hence, for the corresponding HP, the 10th term is 1/38. - 1. A and B are two number whose AM is 25 and GM is 7. Which of the following may be a value of A?
Options- A. 10
- B. 49
- C. 20
- D. 25 Discuss
- 2. How many terms are there in the GP 5, 20, 80, 320, ..., 20480?
Options- A. 7
- B. 6
- C. 5
- D. 10 Discuss
- 3. The fifth term of a GP is 81 and first term is 16. Find the 4th term.?
Options- A. 36
- B. 54
- C. 24
- D. 18 Discuss
- 4. The age of the father of two children is twice that of the elder one added to four times that of the younger one. If the geometric mean of the ages of the two children is 4? 3 and their harmonic mean is 6, then what is the father's age?
Options- A. 48 yr
- B. 32 yr
- C. 40 yr
- D. 56 yr Discuss
- 5. For doing a certain job, boy is offered ? 5 on the first day, ? 15 on the second day, ? 45 on the third day and so no. How much will the boy earn at the end of seven days?
Options- A. ? 5486
- B. ? 5484
- C. ? 5465
- D. ? 5450 Discuss
- 6. If five times the fifth term of an AP is equal to seven times the seventh term of the AP, then what is the twelfth term?
Options- A. - 1
- B. 0
- C. 1
- D. - 2 Discuss
- 7. 2, 8, 18,?, 50, 72
Options- A. 33
- B. 38
- C. 36
- D. 32 Discuss
- 8. 2, 9, 28, 65, 126, .....?
Options- A. 195
- B. 199
- C. 208
- D. 217 Discuss
- 9. 14, 33, 104,?, 2110
Options- A. 421
- B. 433
- C. 372
- D. 840 Discuss
- 10. 840,?, 420, 140, 35, 7
Options- A. 408
- B. 840
- C. 480
- D. 804 Discuss
Odd Man Out and Series problems
Search Results
Correct Answer: 49
Explanation:
(a + b)/2 = 25
a + b = 50
?ab = 7
ab = 49
Hence, A can either be 7 or 49.
So, 49 is the answer.
Correct Answer: 7
Explanation:
Let term = l = arn - 1 a = 5 and l = 20480
r = 20/5 = 4
? 20480 = 5 x (4)n-1
(4)n-1 = 20480/5 = 4096 = (4)6
n - 1 = 6
? n = 7
Correct Answer: 54
Explanation:
The nth term of a GP is arn - 1 ,
5th term = ar5 - 1 = ar4 = 81
1st term = a = 16
? r4 = 81/16
? r = ?81/16 = 3/2
? 4th term = ar4 - 1 = ar3 = 16 x 3/2 x 3/2 x 3/2 = 54
Correct Answer: 40 yr
Explanation:
Given, F = 2E + 4Y ...(I)
?EY = 4?3
? EY = 48 ...(II)
and 2EY/ E + Y = 6 ? E + Y = 16 ...(III)
Now, (E -Y)2 = (E + Y)2 - 4EY
= (16)2 - 4 x 48
= 256 - 192 = 64
? E - Y = 8 ...(iv)
From Eqs. (iii) and (iv), we get
E = 12 and Y = 4
From Eq. (i) F = 2 x 12 + 4 x 4 = 40 yr
Correct Answer: ? 5465
Explanation:
This is a GP with a = 5 , r = 15/5 = 3, n = 7
Sn = a(rn - 1 )/(r - 1)
? S15 = 5(37 - 1)/(3 - 1)
= 5/2(37 - 1)
= 5/2 (2187 - 1)
= ? 5465
Correct Answer: 0
Explanation:
T5 = a + 4d, T7 = a + 6d
? 5(a + 4d) = 7(a + 6d)
? 5a + 20d = 7a + 42d
? a = -11d
? T12 = a + 11d = - 11d + 11d = 0
So, the twelfth term is 0.
Correct Answer: 32
Explanation:
Series pattern
2 x 12, 2 x 22, 2 x 32, 2 x 42, 2 x 52, 2 x 62
? Missing term = 2 x 42 = 32
Correct Answer: 217
Explanation:
Series pattern
13 + 1, 33 + 1, 43 + 1, 53 + 1
? Missing term = 63 + 1 = 217
Correct Answer: 421
Explanation:
Series pattern
x 2 + 5, x 3 + 5, x 4 + 5, x 5 + 5,
? Missing term = 104 x 4 + 5 = 416 + 5 = 421
Correct Answer: 840
Explanation:
Series pattern
÷ 1, ÷ 2, ÷ 3, ÷ 4, ÷ 5
? Missing term = 840/1 = 840
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