CAT Questions

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Since the narrator has no brother, his father’s son is he himself. So, the man who is talking is the father of the man in the photograph. Thus, the man in the photograph is his son.

Two series alternate here, with every third number following a different pattern.
In the main series, 4 is added to each number to arrive the next.
In alternate series, 5 is subtracted from each number t arrive the next number.
Here in the main series
3 + 4 = 7
7 + 4 = 11
11 + 4 = 15
15 + 4 = 19

In alternate series
24 - 5 = 19
19 - 5 = 14...

Here E = 5 = 5/1 = 5

=> READ = 18 + 5 + 1 + 4 = 28/4 = 7

=> DEAR = 4 + 5 + 1 + 18 = 28/4 = 7

The given number series follows a pattern that,

$$\begin{gathered} 19 + 12 = 20 (not 21) \\ 20 + 22 = 24 \\ 24 + 32 = 33 \\ 33 + 42 = 49 \\ 49 + 52 = 74 \end{gathered}$$

Hence, the odd number in the given number series is 21.

Brightness of bulb depends on both voltage and current. The brightness depends on power.

Since we know that  Power (P) = Voltage x Current = V I

So whether you increase the current or the voltage the brightness will increase.

Example Illustration:

 If you connect a long bulb and a round bulb in series, the long bulb glows but the round bulb does not. Both of them have the same current flowing through them (they are in series) but the long bulb has a greater voltage across it because it has more resistance (even though V= IR is not obeyed exactly, voltage drop does depend on the resistance). If you connect a round bulb and a long bulb in parallel, however, it is the round bulb that is brighter because now the voltage across both bulbs is the same but the current is larger through the round bulb (smaller resistance).

Hence, the brightness of a bulb depends on power i.e, both voltage and current.

C alone can finish the work in 40 days.
As given C does half as much work as A and B together
=> (A + B) can do it in 20 days
(A + B)s 1 days wok = 1/20.
A's 1 days work : B's 1 days Work = 1/2 : 1 = 1:2(given)
A's 1 day’s work = (1/20) x (1/3) = (1/60) [Divide 1/20 in the raio 1:2]
B's 1 days work = (1/20) x (2/3) = 1/30
(A+B+C)'s 1 day's work = (1/60) + (1/30) + (1/40) = 9/120 = 3/40

All the three together will finish it in 40/3 = 13 and 1/3 days.

     CP : MP = 2x : 3x

 => Profit = x

( %) profit : (%) discount = 3:2

Let  CP = 2000,  SP = 300

But  3x100×200 + 2x100×300 = 100

=>  x = 8.33%

Discount 2x = 16.66% 

Given number series is 61, 66, 83, 121, 185

Here the given series follows a pattern that,

$$\begin{gathered} 61 \\ 61 + 22 + 1 = 66 \\ 66 + 42 + 1 = 83 \\ 83 + 62 + 1 = 120 (not 121) \\ 120 + 82 + 1 = 185 \end{gathered}$$

Hence, the odd man in the given series is 121.