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4 or 5 digit code with alphabet

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by vittalgmat » Fri Oct 03, 2008 8:20 pm
# of ways a 4 digit code can be created is 26^4.
(ie. 26 ways for each digit => 26*26*26*26.)

Similarly # of ways a 5 digit code can be created is 26^5

Since it is an OR, we add these two
26^4 + 26^5
= 26^4(1 + 26)
= 27 * 26^4

So B is the answer
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by vittalgmat » Fri Oct 03, 2008 8:20 pm
# of ways a 4 digit code can be created is 26^4.
(ie. 26 ways for each digit => 26*26*26*26.)

Similarly # of ways a 5 digit code can be created is 26^5

Since it is an OR, we add these two
26^4 + 26^5
= 26^4(1 + 26)
= 27 * 26^4

So B is the answer
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by stop@800 » Sat Oct 04, 2008 3:07 am
Yes B should be the OA

26^4 + 26^5
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