**Directions (1-5) : In the following number series only one number is wrong. Find out the wrong number.**

1. 4 3 4.5 8.5 20 53 162.5

(a) 3

(b) 4.5

(c) 8.5

(d) 20

### Show Answer

Answer : (c) 8.5

**Explanation :**

(c) The pattern of the number series is

4 * 0.5 + 1 = 2 + 1 = 3

3 * 1 + 1.5 = 3 + 1.5 = 4.5

4.5 * 1.5 + 2 = 6.75 + 2

= 8.75 Not equal to 8.5

8.75 * 2 + 2.5 = 17.5 + 2.5 = 20

20 * 2.5 + 3 = 50 + 3 = 53

2. 12000 2395 472 89.8 12.96 -2.408 -5.4816

(a) -5.4816

(b) 472

(c) 12.96

(d) 2395

### Show Answer

Answer : (b) 472

**Explanation :**

(b) The pattern of the number series is

12000 / 5 – 5 = 24000 – 5 = 2395

2395 / 5 – 5 = 479 – 5

= 474 Not equal to 472

474 / 5 – 5 = 94.8 – 5 = 89.8

89.8 / 5 – 5 = 17.96 – 5 = 12.96

3. 1 8 28 99 412 2075 12460

(a) 28

(b) 99

(c) 412

(d) 12460

### Show Answer

Answer : (d) 12460

**Explanation :**

(d) The pattern of the number series is

1 *1 + 7 * 1 = 1 + 7 = 8

8 * 2 + 6 * 2 = 16 + 12 = 28

28 * 3 + 5 * 3 = 84 + 15 = 99

99 * 4 + 4 * 4 = 396 + 16 = 412

412 * 5 + 3 * 5 = 2060 + 15 = 2075

2075 * 6 + 2 * 6 = 12450 + 12 = 12462 Not equal to 12460

4. 144 215 540 1890 8505 46777.5 304053.75

(a) 215

(b) 540

(c) 1890

(d) 8505

### Show Answer

Answer : (a) 215

**Explanation :**

(a) The pattern of the number series is

144 * 1.5 = 216 Not equal to 215

216 * 2.5 = 540

540 * 3.5 = 1890

1890 * 4.5 = 8505

8505 * 5.5 = 46777.5

5. 2222 1879 1663 1538 1474 1447 1440

(a) 1879

(b) 1538

(c) 1440

(d) 1474

### Show Answer

Answer : (c) 1440

**Explanation:**

(c) The pattern of the number series is

2222 – 7^3 = 2222 – 343 = 1879

1879 – 6^3 = 1879 – 216 = 1663

1663 = 5^3 = 1663 – 125 = 1538

1538 – 4^3 = 1538 – 64 = 1474

1474 – 3^3 = 1474 – 27 = 1447

1447 – 2^3 = 1447 – 8

= 1439 Not equal to 1440

6. In a college, the ratio of boys to girls is 31 : 23 respectively. When 75 more girls join the college, this ratio becomes 124 : 107. How many more girls should join the college to make the number of boys and girls equal?

(a) 75

(b) 90

(c) 65

(d) 85

### Show Answer

Answer : (d) 85

**Explanation:**

(d) Original number of boys in the college = 31x

Original number of girls = 23x

Therefore 31x / 23x + 75 = 124 / 107

= 2852x + 9300 = 3317x

= 3317x – 2852x = 9300

= 465x = 9300

= x = 9300 / 465 = 20

Therefore Number of boys = 31 * 20

= 620

New number of girls

= 23 * 20 + 75 = 535

Therefore Required answer = 620 – 535 = 85

7. The compound interest accured on an amount at the end of two years at the rate of 12 p.c..a is 2,862. What is the amount?

(a) 11, 250

(b) 12, 200

(c) 13, 500

(d) 10, 000

### Show Answer

Answer : (a) 11, 250

**Explanation :**

(a) If the principal be Rs, P, then

C.I. = P [(1 + R / 100)^T-1]

= 2862 = P [(1 + 12 / 100)^2-1]

= 2862 = P[(28 / 25)^2 – 1]

= 2892 = P = (784 – 625 / 625)

= 2862 = P * 159 / 625

Therefore P = 2862 * 625 / 159

= Rs. 11250

8. A 280 metres long train, travelling at a uniform speed, crosees a platform in 60 seconds and a man standing on the platform in 20 seconds, What is the length of the platform?

(a) 640 metres

(b) 420 metres

(c) 280 metres

(d) 560 metres

### Show Answer

Answer : (d) 560 metres

**Explanation :**

(d) When a train crosses a platform it coovers a distance equal to the sum of lengths of platform and train.

Let the length of platform be x metre.

Therefore Speed of train

= x + 280 / 60 = 280 / 20 = 14

= x + 280 = 60 * 14 = 840

Therefore x = 840 – 280 = 560 metre

9. A triangle has two of its angles in the rationof 1 : 2. If the measure of one of its angles is 30 degrees. What is the measure of the largest angle of the triangle in degrees?

(a) 100

(b) 90

(c) 135

(d) None of these

### Show Answer

Answer : (b) 90

**Explanation :**

(b) If the angle be 30degree, then according to ratio,

Second angle = 60degree

Therefore angle = 180degree – 60degree – 30degree = 90 degree

If the given ratio be of two other angles, then

x + 2x = 180degree – 30degree = 150degree

= 3x = 150degree = x = 50degree

Therefore second angle = 2 * 50 = 100degree

Hence, the largest angle

= 90degree or 100degree

10. In how many different ways can the number ‘256974’ be arranged, using each digit only once in each arrangement, such that the digits 6 and 5 are at the extreme ends in each arrangement?

(a) 48

(b) 720

(c) 36

(d) 360

### Show Answer

Answer : (a) 48

**Explanation :**

(a) Case I, 6 / / / / / 5

Four empty places can be filled by 2 9, 7 and 4 in 4! i.e. 4 * 3 * 2 * 1 = 24 ways.

Case II, 5 / / / / / 6

Number of arrangements = 24

Therefore Required number of arrangements = 24 + 24 = 48