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What is the sum of first 10 non-negative even integers? A) 40 B) 90 C
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11 May 2021, 03:44
11 May 2021, 03:44
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Question Stats:
61% (01:07) correct
38% (00:43) wrong based on 18 sessions
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What is the sum of first 10 non-negative even integers?
A) 40
B) 90
C) 100
D) 110
E) 200
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
A) 40
B) 90
C) 100
D) 110
E) 200
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
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Re: What is the sum of first 10 non-negative even integers? A) 40 B) 90 C
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11 May 2021, 05:50
11 May 2021, 05:50
2
Carcass wrote:
What is the sum of first 10 non-negative even integers?
A) 40
B) 90
C) 100
D) 110
E) 200
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
A) 40
B) 90
C) 100
D) 110
E) 200
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
One approach....
We want: 0 + 2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18
Let's add the 10 values in PAIRS, starting with the two outermost values and working inwards.
Notice that 0 + 18 = 18
And 2 + 16 = 18
And 4 + 14 = 18
In fact, when we add the values like this, every pair adds to 18
There are 10 values, so there are 5 pairs (all of which add to 18)
So, the sum = 5 x 18 = 90
Answer: B
Re: What is the sum of first 10 non-negative even integers? A) 40 B) 90 C
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01 Feb 2023, 08:03
01 Feb 2023, 08:03
1
I used the standard formula for summing positive even integers then subtracted the final 20.
Sum of 2 + 4 + 6... + 20, where 20 = 2n, is calculated as (n)(n+1):
= (10)(11) = 110
But since we started at zero and only make it to 18, subtract out that final 20 from 110 and you get 90.
Posted from my mobile device
Sum of 2 + 4 + 6... + 20, where 20 = 2n, is calculated as (n)(n+1):
= (10)(11) = 110
But since we started at zero and only make it to 18, subtract out that final 20 from 110 and you get 90.
Posted from my mobile device
