Since she has seven key the probability that the first one will open the door is

if it takes three attempts to open the door,the probability is

if the three attempts would not work
then the probability that the fourth attempt will open the door is

hope this helps
Answer:
e f f g
3 7 2 3
6 14 14 21
e;g=6:21
e : g=2 : 7
Step-by-step explanation:
Answer:
*Me Dividing 3 3/4 divided by 5 5/8* there you go.
Step-by-step explanation:

negative 24 minus 16x (-1) divided by 6^2 divided by 9
ANSWER
four divided by 81 and than X minus 24