How many 4-digit numbers greater than 7,000 can be formed from the dig

Question

How many 4-digit numbers greater than 7,000 can be formed from the digits 3, 5, 7, 8 and 9? (Assume no digit can be repeated)
 
A. 48 
B. 60 
C. 72 
D. 80 
E. 82

Archit3110 · Answer

possible values
thousandths place ; 7,8,9 ; 3
Hundereds,tens & units place ; 4 *3*2
total 3*4*3*2 ; 72
IMO C

itoyj · Answer

Bunuel  
Shouldn't it be mentioned that no digit can be repeated?
Or we need to assume no digit can be repeated unless given otherwise

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Bunuel · Answer

Edited to avoid confusion. Thank you.

Mohammadmo · Answer

3×4×3×2=72
Option C

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TarPhi · Answer

There are 3 numbers that can take the first place - 7 8 and 9. Consequently, 4 numbers can take the 100s place 3 can take the 10s place and 2 can take the units place. 3*4P3 = 72 Please Kudos

StressTest · Answer

First digit can only be 7,8 or 9 in order to be > 7000

so we get: 3C1 * 4C1 * 3C1 * 2C1 * 1 for all digits => results in 72 possibilities.

firas92 · Answer

Bunuel

Is the OA correct? Please post the OE

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CEdward · Answer

This is a permutation problem.

How many 4-digit numbers greater than 7,000 can be formed from the digits 3, 5, 7, 8 and 9? (Assume no digit can be repeated)

A. 48
B. 60
C. 72
D. 80
E. 82

Since the numbers have to be greater than 7. The first digit can only be 7, 8, or 9.

7 _ _ _ <--- 4P3 = 4! / (4-3)! = 4 x 3 x 2 x 1 = 24 <--- Total # of ways we can get a digit greater than 7000 but less than 8000
8 _ _ _ <--- 4P3 = 4! / (4-3)! = 4 x 3 x 2 x 1 = 24 <--- Total # of ways we can get a digit greater than 8000 but less than 9000
9 _ _ _ <--- 4P3 = 4! / (4-3)! = 4 x 3 x 2 x 1 = 24 <--- Total # of ways we can get a digit greater than 9000 but less than 10000

24 + 24 + 24 = 72

Ans is C

How many 4-digit numbers greater than 7,000 can be formed from the dig

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GMAT Problem Solving (PS) Questions

How many 4-digit numbers greater than 7,000 can be formed from the dig

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

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My Rewards