Answer and Explanation to the Weekly GMAT Question
Tuesday September 16, 2008
Here is the answer to the GMAT question I posted yesterday. (from Integrated Learning.)
Answer: E
Explanation:
In order to find the sum of consecutive numbers, we always follow three steps:
The multiples of five between 23 and 92 are really the numbers starting from 25 and ending with 90. To find the number of numbers, subtract 25 from 90, divide by 5, and add 1:
90 – 25 = 65
65/5 = 13
13 + 1 = 14
2. Find the middle number:
The middle number between 25 and 90 is the average of 25 and 90:
25 + 90 = 115
115/2 = 57.5
3. Multiply:
57.5*14 = 805
Additional Resources:
Answer: E
Explanation:
In order to find the sum of consecutive numbers, we always follow three steps:
- Find the number of numbers
- Find the middle number
- Multiply
The multiples of five between 23 and 92 are really the numbers starting from 25 and ending with 90. To find the number of numbers, subtract 25 from 90, divide by 5, and add 1:
90 – 25 = 65
65/5 = 13
13 + 1 = 14
2. Find the middle number:
The middle number between 25 and 90 is the average of 25 and 90:
25 + 90 = 115
115/2 = 57.5
3. Multiply:
57.5*14 = 805
Additional Resources:
Comments
Not sure if it takes longer to do it that way or to simply add all the multiples of 5 between 25 and 90.
Granted you can only do this because the range is small enough in this question.