CFA Practice Question

There are 410 practice questions for this study session.

CFA Practice Question

How many three-digit numbers can you form using the digits 1, 3, 5, 7, and 9 without a repeating a digit within the number to be formed?
A. 20
B. 60
C. 125

User Contributed Comments 9

User Comment
haarlemmer The solution choose 3 out of 5
5C3
this three number can be arranged in order
3!
the answer
5C3*3!
johnsk It's a permutation: 135 != 315 so the order does matter. 3P5 = 5!/(5-3)! = 60.
Eckhardt1978 5!/(5-3)!
armanaziz Note: nPr = n!/(n-r)!
nCr = n!/(n-r)!r!
dealsoutlook its 5P3 and not 3P5
sheenalim ok, what if the number to be formed can have only 2 repeated digits? i think the answer would be:

5 x 4 x 4 = 80

correct me if i'm wrong.
clarelau Sheennalim: Repeated digits are not allowed. SO either 335 or 333 is incorrect. It's 5P3=60
peteypete you dont need the nPr just 5x4x3
Rsanches 5!/(5-3)!=60
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