CAT Questions

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

Let’s break it down. The product of their ages is 72. So what are the possible choices?

2, 2, 18 – sum(2, 2, 18) = 22
2, 4, 9 – sum(2, 4, 9) = 15
2, 6, 6 – sum(2, 6, 6) = 14
2, 3, 12 – sum(2, 3, 12) = 17
3, 4, 6 – sum(3, 4, 6) = 13
3, 3, 8 – sum(3, 3, 8 ) = 14
1, 8, 9 – sum(1,8,9) = 18
1, 3, 24 – sum(1, 3, 24) = 28
1, 4, 18 – sum(1, 4, 18) = 23
1, 2, 36 – sum(1, 2, 36) = 39
1, 6, 12 – sum(1, 6, 12) = 19

The sum of their ages is the same as your birth date. That could be anything from 1 to 31 but the fact that Jack was unable to find out the ages, it means there are two or more combinations with the same sum. From the choices above, only two of them are possible now.

2, 6, 6 – sum(2, 6, 6) = 14
3, 3, 8 – sum(3, 3, 8 ) = 14

Since the eldest kid is taking piano lessons, we can eliminate combination 1 since there are two eldest ones. The answer is 3, 3 and 8.

The dog was sitting under the table waiting to catch the ball that was thrown towards him by his master.

The given number series is 125,   138,   164,   ?,   255

125

125 + 13x1 = 138

138 + 13x2 = 164

164 + 13x3 = 203

203 + 13x4 = 255

Hence, the missing number in the series is 203.

Here in the given series, it follows a pattern that

77 + 2 = 79

79  - 3 = 76

76 + 5 = 81

81 -  7 = 74

74 + 11 = 85

Consecutive adding and subtracting of prime numbers.

So the wrong number in the given series is 75.

a+b=5   ...(1)    and    3a+2b=20 ...(2)

Multiplying (1) by 2 and subtracting from (2), we get : a=10.

Putting a=10 in (1), we get : b=-5

Therefore,   (3a+b) = 3 x 10+(-5)=30-5=25.

Here the series has mixed two series.
n m l k...! reverse alphabet
o p q r ...! forward alphabet
So the letter before k is j and after that letter after r is s and so on...

  4             3             4             7               15        ?
×1-1      ×1+1       ×2-1       ×2+1           ×3-1

15x3 - 1 = 45 - 1 = 44