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# RBI Grade B Quantitative Aptitude Questions PDF:

We have provided some RBI Grade-B Quantitative Aptitude questions and answers with detailed explanations. Quant section will have 30 questions in RBI Grade-B exam.

Instructions (1 – 5): In the following number series only one number is wrong. Find out the wrong number.

Question 1: 18.3, 20.6, 16, 22.9, 13.7, 2.2, 11.4

a) 2.2
b) 16
c) 22.9
d) 20.6
e) 13.7

Question 2: 2, 4, 11, 37, 151, 771, 4633

a) 151
b) 4
c) 37
d) 771
e) 11

Question 3: 188, 154, 140, 132, 128, 126, 125

a) 154
b) 132
c) 128
d) 140
e) 126

Question 4: 6, 4, 5, 11, 39, 179, 1127

a) 4
b) 39
c) 179
d) 5
e) 11

Question 5: 9, 5, 6, 10.5, 23, 61, 183

a) 61
b) 23
c) 10.5
d) 6
e) 5

Instructions (6 – 10): What will come in place of the question mark (?) in the following number series ?

Question 6: 9, 31, 73, 141, (?)

a) 164
b) 280
c) 239
d) 241
e) None of these

Question 7: 35, 256, 451, 620, 763, (?)

a) 680
b) 893
c) 633
d) 880
e) None of these

Question 8: 130, 139, 155, 180, 216, (?)

a) 260
b) 290
c) 265
d) 996
e) None of these

Question 9: 2890, (?), 1162, 874, 730, 658

a) 1684
b) 1738
c) 1784
d) 1672
e) None of these

Question 10: 14, 1004, 1202, 1251.5, 1268, (?)

a) 1267.5
b) 1276.25
c) 1324.5
d) 1367.25
e) None of these

Solutions:

Multiples of 2.3 are alternatively added and subtracted.
$18.3 + (2.3 \times 1) = 20.6$
$20.6 – (2.3 \times 2) = 16$
$16 + (2.3 \times 3) = 22.9$
$22.9 – (2.3 \times 4) = 13.7$
$13.7 + (2.3 \times 5) = 25.2 $$\neq 2.2$$=$$25.2 – (2.3 \times 6) = 11.4$

The pattern followed is :
2 $\times 1 + 2$ = 4
4 $\times 2 + 3$ = 11
11 $\times 3 + 4$ = 37
37 $\times 4 + 5$ = 153 $\neq 151$
153 $\times 5 + 6$ = 771
771 $\times 6 + 7$ = 4633

Successive powers of 2 are subtracted.
188 $- 2^5$ = 156 $\neq 154$
156 $- 2^4$ = 140
140 $- 2^3$ = 132
132 $- 2^2$ = 128
128 $- 2^1$ = 126
126 $- 2^0$ = 125

The pattern followed is :
6 $\times 1 – 2$ = 4
4 $\times 2 – 3$ = 5
5 $\times 3 – 4$ = 11
11 $\times 4 – 5$ = 39
39 $\times 5 – 6$ = 189 $\neq 179$
189 $\times 6 – 7$ = 1127

The series follows the following pattern:
9 * 0.5 + 0.5 = 5
5*1 + 1 = 6
6 * 1.5 + 1.5 = 10.5
10.5 * 2 + 2 = 23
23 * 2.5 + 2.5 = 60
60 * 3 + 3 = 183
Hence, 61 is the incorrect number.

The pattern followed is :
$2^3 + 1^2$ = 9
$3^3 + 2^2$ = 31
$4^3 + 3^2$ = 73
$5^3 + 4^2$ = 141
$6^3 + 5^2$ = 241

The pattern followed is :
35 + 221 = 256
256 + (221 – 26) = 256 + 195 = 451
451 + (195 – 26) = 451 + 169 = 620
620 + (169 – 26) = 620 + 143 = 763
763 + (143 – 26) = 763 + 117 = 880

Squares of natural number starting from 3 are added
130 $+ 3^2$ = 139
139 $+ 4^2$ = 155
155 $+ 5^2$ = 180
180 $+ 6^2$ = 216
216 $+ 7^2$ = 265

Numbers of the form $(72 \times 2^n)$ is subtracted where n is whole number
2890 $- 72 \times 2^4$ = 1738
1738 $- 72 \times 2^3$ = 1162
1162 $- 72 \times 2^2$ = 874
874 $- 72 \times 2^1$ = 730
730 $- 72 \times 2^0$ = 658

1202 – 1004 = 198 = $(\frac{990}{5})$
1251.5 – 1202 = 49.5 = $(\frac{198}{4})$
1268 – 1251.5 = 16.5 = $(\frac{49.5}{3})$
$\therefore$ 1268 + $\frac{16.5}{2}$ = 1276.25