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A company plans to assign identification numbers to its employees. Eac

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A company plans to assign identification numbers to its employees. Eac  [#permalink]

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New post 02 Oct 2018, 01:50
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  25% (medium)

Question Stats:

68% (00:58) correct 32% (00:58) wrong based on 47 sessions

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A company plans to assign identification numbers to its employees. Each number is to consist of four digits from 0 to 9, inclusive, except that the first digit cannot be 0. If any digit can be repeated any number of times in a particular code, how many different identification numbers are possible that are odd numbers?

(A) 2520
(B) 2268
(C) 3240
(D) 4500
(E) 9000

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Joined: 29 Dec 2017
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Re: A company plans to assign identification numbers to its employees. Eac  [#permalink]

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New post 05 Oct 2018, 17:54
1: 9 options (digits 1-9)
2: 10 options (digits 0-9)
3: 10 options (digits 0-9)
4: 5 options (only odd digits 1,3,5,7,9)

Total options = 9 x 10 x 10 x 5 = 4 500

Answer D.
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Re: A company plans to assign identification numbers to its employees. Eac  [#permalink]

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New post 06 Oct 2018, 03:07
Hero8888 wrote:
1: 9 options (digits 1-9)
2: 10 options (digits 0-9)
3: 10 options (digits 0-9)
4: 5 options (only odd digits 1,3,5,7,9)

Total options = 9 x 10 x 10 x 5 = 4 500

Answer D.


Can you elaborate this method.

I did this question in the below way.

4 digit numbers and it should not start with a zero. So there are 9000 numbers between 1000-9999.

There are 5 odd and 5 even numbers in every 10 numbers. Hence there are 4500 odd number identifications.

Do you think this method is correct?

Thanks in advance
Arjun
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Joined: 29 Dec 2017
Posts: 389
Location: United States
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GMAT 3: 710 Q50 V37
GPA: 3.25
WE: Marketing (Telecommunications)
A company plans to assign identification numbers to its employees. Eac  [#permalink]

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New post 06 Oct 2018, 07:32
1
ArjunJag1328 wrote:
Hero8888 wrote:
1: 9 options (digits 1-9)
2: 10 options (digits 0-9)
3: 10 options (digits 0-9)
4: 5 options (only odd digits 1,3,5,7,9)

Total options = 9 x 10 x 10 x 5 = 4 500

Answer D.


Can you elaborate this method.

I did this question in the below way.

4 digit numbers and it should not start with a zero. So there are 9000 numbers between 1000-9999.

There are 5 odd and 5 even numbers in every 10 numbers. Hence there are 4500 odd number identifications.

Do you think this method is correct?

Thanks in advance
Arjun


There is nothing wrong with your method, yet if you want a good score on Quant section, you have to master basic understanding of combinations/permutations. Just think logically, going through the question. You have 4 slots __ __ __ __.

1st can not be 0, so you have 9 digits to fill the slot
2nd and 3rd have no limitations, so you can fill them each with all 10 digits.
4st should be odd, so you have 5 digits to fill the slot (1,3,5,7,9)

To find total number, multiply options in 4 slots 9*10*10*5 = 4500
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Re: A company plans to assign identification numbers to its employees. Eac  [#permalink]

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New post 06 Oct 2018, 08:00
Hero8888 wrote:
ArjunJag1328 wrote:
Hero8888 wrote:
1: 9 options (digits 1-9)
2: 10 options (digits 0-9)
3: 10 options (digits 0-9)
4: 5 options (only odd digits 1,3,5,7,9)

Total options = 9 x 10 x 10 x 5 = 4 500

Answer D.


Can you elaborate this method.

I did this question in the below way.

4 digit numbers and it should not start with a zero. So there are 9000 numbers between 1000-9999.



There are 5 odd and 5 even numbers in every 10 numbers. Hence there are 4500 odd number identifications.

Do you think this method is correct?

Thanks in advance
Arjun


There is nothing wrong with your method, yet if you want a good score on Quant section, you have to master basic understanding of combinations/permutations. Just think logically, going through the question. You have 4 slots __ __ __ __.

1st can not be 0, so you have 9 digits to fill the slot
2nd and 3rd have no limitations, so you can fill them each with all 10 digits.
4st should be odd, so you have 5 digits to fill the slot (1,3,5,7,9)

To find total number, multiply options in 4 slots 9*10*10*5 = 4500


Nice explanation. Thank you :)
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Re: A company plans to assign identification numbers to its employees. Eac &nbs [#permalink] 06 Oct 2018, 08:00
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