Question

"Elijah forgot his pass code for a certain website. He knows it is made up of 4 digits and no digit can be repeated. If he randomly chooses 4 digits, what is the probability that he chooses his pass code?"

A. 1/5040
B. 1/1260
C. 1/210
D. 1/24

Answer 1

D

Answer 2

How did you get D?

Answer 3

There are 10*9*8*7 = 5040 different ways to have a 4-digit password where no repeats are allowed

Answer 4

there is only 1 way to have your 4-digit password

so the probability is 1/5040

Answer 5

Thanks!

Answer 6

np

Answer 7

yep the answer is A

Answer 8

I've got just one more question, if that's alright:
"Lidia is packing her suitcase in the dark, so as to not wake her sister. She blindly chooses 3 of her 5 sweaters. What is the probability that she chose her 3 favorite sweaters?"

A. 1/10
B. 1/15
C. 1/60
D. 1/75

Answer 9

Assuming order doesn't matter, there's only one way to choose her 3 favorite sweaters (to fill the 3 slots)

This is out of 5 C 3 = (5!)/(3!*(5-3)!) = 10 different ways to pick 3 sweaters (from 5 total)

Answer 10

Thank you, again!

Answer 11

sure thing