GATE Questions

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6-3 = 3 9-4 = 5 (3x5=15) 15=O
7-2 = 5 7-3 = 4 (5x4=20) 20=T
9-6 = 3 5-1 = 4 (3x4=12) 12=L

Similarly, 4-1 = 3 8-5 = 1 (3x1=3) 3=C

The terms of the series are products of two consecutive prime numbers i.e.

(2 x 3), (3 x 5), (5 x 7), (7 x 11),.....

So, 165 is wrong and must be replaced by (11 x 13) i.e. 143.

$$\begin{gathered} ?2 = 2×78-21+8+49-148 \\ = 57 - 21 \\ =36 \\ => ? = ±6 \end{gathered}$$

Given 311   230   294   ?   281   256

311 - (9x9) = 230

230 + (8x8) = 294

294 - (7x7) = 245

245 + (6x6) = 281

281 - (5x5) = 256

Hence, the missing number in the given series is 245.

A person or animal must take in oxygen for respiration to occur. A mouth (choice a) is not essential because breathing can occur through the nose. Choices b and d are clearly not essential and can be ruled out.

Here given 

2, 3, 6, 15, ? , 157.5

2 x 1.5 = 3

3 x 2  = 6

6 x 2.5 = 15

15 x 3 = 45

45 x 3.5 = 157.5

Therefore, the missing number is 45

1397 x 1397

Lethargic means "sluggish", kind of inactive

Vital means full of energy, lively

So, they are antonyms.

So, for the 2nd part of the analogy, you are looking for a antonym to trite

Trite means lacking originality or freshness. Overused. Kind of like a cliche

So, an antonym could be original, unique, innovative.