g.shankaran wrote:if x is equal to the sum of the even integers from 40 to 60, inclusive and y is the number of even integers from 40 to 60, inclusive what is the value of x + y?
1. 550
2. 551
3. 560
4. 561
5. 571
To determine the sum of evenly spaced integers, use the following formula:
Sum = (number of integers) * (average of biggest and smallest)
To count the number of evenly spaced integers in a set:
Number of integers = (Biggest - Smallest)/(distance between each successive pair) + 1
With even integers, the distance between each successive pair is 2.
Thus, given the even integers from 40 to 60, inclusive:
Number of integers = (60-40)/2 + 1 = 11.
Average of biggest and smallest = (60+40)/2 = 50.
Sum = number * average = 11*50 = 550.
Sum + number = 550+11 = 561.
The correct answer is
D.
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