# Online Coaching For RRB Exam Reasoning (Mathematical Operations)

Submitted by staff on Thu, 2016-01-21 16:03

## Online Coaching For RRB Exam

## Reasoning (Mathematical Operations)

The basic approach for the problems of this type is more or less similar to that of coding and decoding. One has to study the symbols or the geometrical figures and their meanings carefully. Then, the meanings are to be used in place of those symbols in answering the questions.

**The questions can be categorised into two types:**

__Symbols and Notations__

**Example 2: If 2 * 3 = 12, 3 * 4 = 20 and 4 * 5 = 30, then 2 * 6 is**

(a) 18

(b) 12

(c) 21

(d) None of these

**Solution. (c)** The numbers on both sides of * are
increased by one and then multiplied to get the answer.

2*6 = 3 × 7 = 21

**Example 3: If x + y = (x + y + xy –1) (x + y + xy + 1),
then the value of (4 $ 10) is**

(a) 2915

(b) 2195

(c) 2951

(d) 2955

**Solution. (a)** As per the definition of +, (4+10) would
be (4 + 10 + 4 × 10 – 1) (4 + 10 + 4 × 10 + 1) = 2915. So, answer is (a)

**Example 4: If * means “is greater than”, @ means `is less
than’; and $ means “is equal to” and if a + b and b @ c, then**

(a) c * b

(b) b * c

(c) c * a

(d) Both (a) and (c)

**Solution. (d) **Replace the symbols with the meaning
given against them. If a $ b and b @ c would become a = b and b < c, then c > b
or c > a ie, c * b, c * a are true from the given options.

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