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?
550
551
560
561
572
Guys I applied the formula for "sum of consecutive evn nos." but i am going wrong somewhere.Pease help.
y=11
x=sum of consecutive even integers=n(n+1)
where n= 1st even+last even/2 -1
Therefore,here n=40+60/2-1=50-1=49
So,x=49 x 50 =2450
Hence, x+y=2450+11=2461??!??!
sum of the even integers from 40 to 60 inclusive
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For consecutive integer problems or any evenly spaced problems use this formula:uptowngirl92 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?
550
551
560
561
572
Guys I applied the formula for "sum of consecutive evn nos." but i am going wrong somewhere.Pease help.
y=11
x=sum of consecutive even integers=n(n+1)
where n= 1st even+last even/2 -1
Therefore,here n=40+60/2-1=50-1=49
So,x=49 x 50 =2450
Hence, x+y=2450+11=2461??!??!
Number of terms = {[last term - first term] / increment } + 1
Here, increment = 2 since it is mentioned they are even consecutive numbers. Last term = 60 first term = 40
so Number of terms = {[60 - 40] / 2} + 1 = 11
Sum = Average * number of terms
Average of the even integers from 40 to 60 is simply average of the first and the last terms which gives us [40+60]/2 = 50
Sum = 50 * 11 = 550 = x
Number of terms = y = 11
x + y = 550 + 11 = 561
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- Master | Next Rank: 500 Posts
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- Joined: Sun Apr 19, 2009 9:08 pm
- Location: Kolkata,India
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- GMAT Score:670
thanks guys i got the answer but I still dont know where im going wrong!!am i following the formulae wrong??please refer to link below from where i got the formula:
https://www.beatthegmat.com/formula-for- ... 17241.html
https://www.beatthegmat.com/formula-for- ... 17241.html