Question Details

Directions (55-57): Read the following table carefully and answer the questions given below.

In the table some numbers are given and the probability of picking that number is given.

NUMBERS Probability
Q
16
2.5
13
Q − 2.5
13
P
16
4Q5 2
16
18.75
16

If the series ‘Q,  2.5,  Q − 2.5,  P,  4Q5 2 ,  18.75’  follows a certain pattern, then find the value of P.

Options

A

3.5

B

3.75

C

4

D

5

E

2.75

Show Answer

Correct Answer :

Option B

3.75

3.75

Solution :

To find the value of P, we need to determine the mathematical pattern followed by the given sequence:
Q,2.5,Q-2.5,P,4Q-5,2,18.75

Let us examine the relationship between consecutive terms. Let the terms of the series be denoted by
a1=Q
a2=2.5
a3=Q-2.5
a4=P
a5=4Q-52
a6=18.75

Let's test a multiplication-addition/subtraction pattern. Specifically, let's assume each term is obtained by multiplying the previous term by a factor that increases or decreases, and adding/subtracting a value.
Let's consider the relation between the first three terms:
If a2=a1×1-2.5, then 2.5=Q-2.5Q=5.

Let us check if Q=5 makes the sequence consistent:
If Q=5, the terms become:
a1=5
a2=2.5
a3=5-2.5=2.5
a5=4(5)-52=152=7.5
a6=18.75

Now let's find the pattern for the sequence 5,2.5,2.5,P,7.5,18.75:
1. a2=a1×0.5=5×0.5=2.5
2. a3=a2×1.0=2.5×1=2.5
3. a4=a3×1.5=2.5×1.5=3.75
4. a5=a4×2.0=3.75×2=7.5
5. a6=a5×2.5=7.5×2.5=18.75

The pattern perfectly holds for all terms, where each term is multiplied by a multiplier that increases by 0.5 at each step (×0.5,×1,×1.5,×2,×2.5).
Therefore, the value of P is:
P=3.75

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