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Question

P, Q, R, S, T, A and B are consecutive integers (not necessarily in that order), such that the smallest of these is greater than 60 and the greatest is less than 70. It is known that:
(I) A and B both are prime numbers.
(II) T is a multiple of 9.
(III) Both the digits of P are same.
(IV) The average of R and S is 63 and the difference between R and S is 2.

What is the sum of A and Q if A is smaller than B?

The correct answer is
126

Consecutive Integers Range Determination

The problem states we are dealing with 7 consecutive integers. Let these integers be represented as $n, n+1, n+2, n+3, n+4, n+5, n+6$. We are given two conditions regarding the smallest and greatest of these integers:

  • The smallest integer is greater than 60. This means $n > 60$.
  • The greatest integer is less than 70. This means $n+6 < 70$, which simplifies to $n < 64$.

Combining these inequalities, we find that $60 < n < 64$. The possible integer values for $n$ are 61, 62, and 63.

Let's examine the sets of 7 consecutive integers for each possible value of $n$:

  • If $n=61$, the set is $\{61, 62, 63, 64, 65, 66, 67\}$. The smallest is 61 (which is > 60) and the greatest is 67 (which is < 70). This set is valid.
  • If $n=62$, the set is $\{62, 63, 64, 65, 66, 67, 68\}$. The smallest is 62 (> 60) and the greatest is 68 (< 70). This set is also valid.
  • If $n=63$, the set is $\{63, 64, 65, 66, 67, 68, 69\}$. The smallest is 63 (> 60) and the greatest is 69 (< 70). This set is also valid.

Prime Number Clue Assignment

Clue (I) states that A and B are both prime numbers. We need to find which of the possible sets contains exactly two prime numbers.

  • In the set $\{61, 62, 63, 64, 65, 66, 67\}$, the prime numbers are 61 and 67. This set allows for two distinct prime numbers, A and B.
  • In the set $\{62, 63, 64, 65, 66, 67, 68\}$, the only prime number is 67. This set does not allow for two distinct prime numbers A and B.
  • In the set $\{63, 64, 65, 66, 67, 68, 69\}$, the only prime number is 67. This set also does not allow for two distinct prime numbers A and B.

Therefore, the correct set of 7 consecutive integers must be $\{61, 62, 63, 64, 65, 66, 67\}$. From this set, the prime numbers are 61 and 67. Thus, $\{A, B\} = \{61, 67\}$.

Multiple of 9 and Same Digit Clues

Let's use the other clues to identify the remaining variables:

  • Clue (II): T is a multiple of 9. In the confirmed set $\{61, 62, 63, 64, 65, 66, 67\}$, the only multiple of 9 is 63. So, T = 63.
  • Clue (III): Both the digits of P are same. In the set $\{61, 62, 63, 64, 65, 66, 67\}$, the number with identical digits is 66. So, P = 66.

Average and Difference Clues for R and S

Clue (IV): The average of R and S is 63 and the difference between R and S is 2.

We can set up equations based on this clue:

  • The average of R and S is 63: $ \frac{R+S}{2} = 63 $ Multiplying both sides by 2 gives: $ R+S = 126 $
  • The difference between R and S is 2. Assuming $R$ is the larger number, we have: $ R-S = 2 $

Now we solve this system of two linear equations:

  1. $R+S = 126$
  2. $R-S = 2$

Adding equation (1) and equation (2):

$ (R+S) + (R-S) = 126 + 2 $ $ 2R = 128 $ $ R = \frac{128}{2} = 64 $

Substitute the value of $R$ back into equation (1):

$ 64 + S = 126 $ $ S = 126 - 64 = 62 $

So, R = 64 and S = 62. Both these numbers are present in our confirmed set $\{61, 62, 63, 64, 65, 66, 67\}$.

Identifying Q and A Value

We have assigned values to T, P, R, and S from the set $\{61, 62, 63, 64, 65, 66, 67\}$:

  • T = 63
  • P = 66
  • R = 64
  • S = 62
  • A and B are the primes: 61 and 67.

The only integer remaining in the set that has not been assigned a variable is 65. The only variable left unassigned is Q. Therefore, Q = 65.

The question asks for the sum of A and Q, given that A is smaller than B. Since $\{A, B\} = \{61, 67\}$ and A must be smaller:

  • A = 61

Final Sum Calculation

We need to calculate the sum of A and Q.

  • A = 61
  • Q = 65

The sum is:

$ A + Q = 61 + 65 = 126 $

The sum of A and Q is 126.

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Important Questions from Puzzle (Notes)

  1. Four individuals - P, Q, R and S - are suspects in a theft case. They make the following statements :
    P says: "Q is guilty."
    Q says: "R is guilty."
    R says: "P is innocent."
    S says: "I am innocent"
    If it is known that exactly one of them is guilty, and only the guilty person lies (all innocent people tell the truth), then who is the guilty one?
  2. In which company, C's interview was scheduled?
  3. Who went to Nagpur?
  4. What is the sum of the digits of the number Q?
  5. There are five men - A, B, C, D and E, six women P, Q, R, S, T and Z. A, B, and R are advocates. S, Q, P, D and C are doctors and the rest are teachers. A team has to be selected from these eleven persons subject to the following conditions:
    (I) A, P and Z have to be together.
    (II) B cannot go with D or R.
    (III) E and Q have to be together.
    (IV) C and T have to be together.
    (V) D and P cannot go together.
    (VI) C cannot go with Q.
    If the team formed consists of two male advocates, two lady doctors and one teacher, the members of the team can be:
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