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: SQUARE ROOT OF 8
Step-by-step explanation: 2^3^1/2 is SQUARE ROOT OF 8. GOD BLESS
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Linear is correct credit to the person above
<span>So there
are 33 boys who tried out for track. And this is 27.5 % of the total boys. And there
15% of the girls who tried out for the track. And in total 22.5 % of the total
population tried out for track</span>