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Question

The product of three integers X, Y and Z is 192. Z is equal to 4 and P is equal to the average of X and Y. What is the minimum possible value of P? 

The correct answer is

7

Understanding the Problem: Minimum Average of Integers

The question asks us to find the minimum possible value of P, where P is the average of two integers X and Y. We are given that the product of three integers X, Y, and Z is 192, and Z is specifically 4.

Breaking Down the Given Information

Let's list out the facts provided:

  • The product of three integers X, Y, and Z is 192. Mathematically, this can be written as: \( \text{X} \times \text{Y} \times \text{Z} = 192 \)
  • The value of Z is given as 4.
  • P is defined as the average of X and Y. This means: \( \text{P} = \frac{\text{X} + \text{Y}}{2} \)

Our goal is to find the smallest possible value for P.

Calculating the Product of X and Y

We know \( \text{X} \times \text{Y} \times \text{Z} = 192 \) and \( \text{Z} = 4 \). We can substitute the value of Z into the first equation:

\( \text{X} \times \text{Y} \times 4 = 192 \)

To find the product of X and Y, we divide both sides by 4:

\( \text{X} \times \text{Y} = \frac{192}{4} \)

\( \text{X} \times \text{Y} = 48 \)

So, we are looking for two integers X and Y whose product is 48. Both X and Y must be integers.

Finding Pairs of Integers (X, Y) for a Product of 48

To minimize the average \( \text{P} = \frac{\text{X} + \text{Y}}{2} \), we need to minimize the sum \( \text{X} + \text{Y} \). For a fixed positive product of two integers, their sum is minimized when the two integers are as close to each other as possible. Since the options provided are all positive, we will consider positive integer pairs for X and Y.

Let's list the positive integer pairs (factors) of 48 and calculate their sum (X+Y) and the average P:

X Y Product (\( \text{X} \times \text{Y} \)) Sum (\( \text{X} + \text{Y} \)) Average (\( \text{P} = \frac{\text{X} + \text{Y}}{2} \))
1 48 48 \( 1 + 48 = 49 \) \( \frac{49}{2} = 24.5 \)
2 24 48 \( 2 + 24 = 26 \) \( \frac{26}{2} = 13 \)
3 16 48 \( 3 + 16 = 19 \) \( \frac{19}{2} = 9.5 \)
4 12 48 \( 4 + 12 = 16 \) \( \frac{16}{2} = 8 \)
6 8 48 \( 6 + 8 = 14 \) \( \frac{14}{2} = 7 \)

From the table, we can see that as X and Y get closer to each other, their sum decreases. The closest positive integer pair for 48 is (6, 8).

Minimum Possible Value of P

By examining the calculated values of P in the table, the minimum positive value for P occurs when X and Y are 6 and 8 (or 8 and 6), which gives a sum of 14. The average P is then:

\( \text{P} = \frac{6 + 8}{2} = \frac{14}{2} = 7 \)

Therefore, the minimum possible value of P is 7.

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Important Questions from Numerical Computation

  1. A cube of side 3 units is formed using a set of smaller cubes of side 1 unit. Find the proportion of the number of faces of the smaller cubes visible to those which are NOT visible.

  2. What is the average of all multiples of 10 from 2 to 198?

  3. Ratio of the angles of a triangle are 1 : 2 : 6. What is the smallest angle?

  4. A deposit in a bank, which pays interest on its deposits compounded daily, grows to Rs. 80,000 for 500 days and to 88,000 for 1000 days. What would be its value (in Rs.) for 1500 days?

  5. Among A, B, C and D, there is a lawyer, a doctor, a teacher and a journalist. They drink exactly one each of tea, coffee, lemonade and milk. If neither the lawyer nor the teacher drinks milk, B drinks coffee, A is the teacher and C is the doctor and drinks tea, then which of the following is FALSE?

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