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begin or end with 3

by sanju09 » Fri Jul 23, 2010 4:02 am
How many integers between 200 and 400 begin or end with 3?
A. 20
B. 60
C. 100
D. 110
E. 120

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by pathaniaus » Fri Jul 23, 2010 4:09 am
I choose E.
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by selango » Fri Jul 23, 2010 4:12 am
end with 3-20

begin with 3-100

Total-120
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by kvcpk » Fri Jul 23, 2010 4:14 am
Numbers that begin with 3:
3XX
places can be filled in 10*10 = 100 ways
Numbers that end with 3:
XX3
Forst place cant be filled by 3 because, we have already counted it.
So first place can be filled only with 2
so 1*10 = 10 ways

total 110 ways
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by selango » Fri Jul 23, 2010 4:16 am
yup..its 110 ways.
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by outreach » Fri Jul 23, 2010 4:25 am
how is it 120?

300-399 have 100 numbers in the set. Every number has a 3 in it because it starts with 3** so that's 100.

200-299 have 19 (3, 13, 23, 30-39, 43, 53, 63, 73, 83, 93)

so my answer is 119.
sanju09 wrote:How many integers between 200 and 400 begin or end with 3?
A. 20
B. 60
C. 100
D. 110
E. 120

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by pathaniaus » Fri Jul 23, 2010 4:33 am
oh stupid mistake by me. i mis-read. thought it stated "200 to 500".
in reference to the last post by outreach, you cannot include 230-239 in 200 to 299 because those numbers dont begin or end with 3. 3 is in the middle, except with 233.
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