Direction[1-3]: What should come in place of the question mark (?) in the following number series?
1. 30 , 62 , 189 , ? , 3805 , 22836
A. 860
B. 760
C. 560
D. 555
E. 654
2. 1.5 , 2.5 , 6 , 19 , 77 , ?
A. 420
B. 99
C. 126
D. 386
E. 102
3. 140, 133, 119, 98, ?, 35
A. 70
B. 45
C. 30
D. 72
E. 61
4. On 1st January, 2000 the average age of a family of 6 people was 'A' years. After 5 years a child was born in the family and one year after that the average age was again found to be 'A' years. What is the value of 'A'? (Assume that there are no other deaths and births.)
A. 28
B. 33
C. 46
D. 56
E. 37
5. Two trains for Mumbai leave Delhi at 6 am and 6:45 am and travel at 100 kmph and 136 kmph respectively. Approx. how many km from Delhi will the two trains be together?
A. 208 km
B. 283 km
C. 324 km
D. 378 km
E. None of these
Answers and Explanations
1. Answer - Option B
Explanation -
30 × 2 + 2 = 62
62 × 3 + 3 = 189
189 × 4 + 4 = 760
760 × 5 + 5 = 3805
3805 × 6 + 6 = 22836
30 , 62 , 189 , 760 , 3805 , 22836
Hence, option B is correct.
2. Answer - Option D
Explanation -
3. Answer - Option A
Explanation -
The Pattern is:-
140
140 - 7 = 133
133 - 14 = 119
119 - 21 = 98
98 - 28 = 70
70 - 35 = 35
Thus, the missing number is 70
So option (A) is the correct answer
4. Answer - Option E
Explanation -
Initially, the total age of the family is 6A (as average age of family is A and number of members in the family is 6)
Five years down the line the total age will increase by : 6*5
Then a child is born in the family and the total number of members now are 7, after a year total age will increase by 7*1
Given that, the average is still then A, so we can write the equation as:
6A + 6*5 + 7*1 = 7A ⇒ A = 37
5. Answer - Option B
Explanation -
In 45 min, 1st train will cover = [latex] 100 \times [\frac {45}{60}][/latex] = 75 km distance.
Relative speed of trains = 136 - 100 = 36 kmph.
2nd train will catch up the 1st train in = [latex]\frac {75}{36} = \frac {25}{12} [/latex]hours.
Distance from Delhi = [latex][\frac {25}{12}] \times 136 [/latex] = 283 km approx.