Question

If the mean of \( x, y, 3, 4 \) is 5, then \( x + y = ? \)

• A. 8
• B. 13
• C. 15
• D. 9

Hint:

To find the sum of numbers when the mean is given, use the formula \( \text{Mean} = \frac{\text{Sum of terms}}{\text{Number of terms}} \) and solve for the sum.

Answer 1

The Correct Option is B

We are given that the mean of \( x, y, 3, 4 \) is 5. Step 1: The formula for the mean of four numbers is: \[ \text{Mean} = \frac{x + y + 3 + 4}{4} \] Step 2: Substituting the given mean value (5): \[ 5 = \frac{x + y + 3 + 4}{4} \] Step 3: Simplify the equation: \[ 5 = \frac{x + y + 7}{4} \] \[ 5 \times 4 = x + y + 7 \] \[ 20 = x + y + 7 \] \[ x + y = 20 - 7 = 13 \] Thus, \( x + y = 13 \).