GMAT Practice Question: If the average (arithmetic mean) of 5 numbers j, j+5,2 j-1,4 j-2, and 5 j-1...
Question
If the average (arithmetic mean) of 5 numbers j, j+5,2 j-1,4 j-2, and 5 j-1 is 8 , what is the value of j ?
- \frac{1}{3}
- \frac{7}{13}
- 1
- 3
- 8
Topics: mean, linear equations
Solution
Step 1
We translate the average condition: the sum of the five numbers equals 5 times 8.
j + (j + 5) + (2j - 1) + (4j - 2) + (5j - 1) = 5 \times 8
Step 2
We combine like terms by grouping the j terms and the constant terms.
j + j + 2j + 4j + 5j + 5 - 1 - 2 - 1 = 40 13j + 1 = 40
Step 3
We isolate the term with j by subtracting 1 from both sides.
13j + 1 - 1 = 40 - 1 13j = 39
Step 4
We solve for j by dividing both sides by 13.
j = \frac{39}{13} = 3
Answer
3
