Answer:
The probability is 0.9211
Step-by-step explanation:
Let's call K the event that the student know the answer, G the event that the student guess the answer and C the event that the answer is correct.
So, the probability P(K/C) that a student knows the answer to a question, given that she answered it correctly is:
P(K/C)=P(K∩C)/P(C)
Where P(C) = P(K∩C) + P(G∩C)
Then, the probability P(K∩C) that the student know the answer and it is correct is:
P(K∩C) = 0.7
On the other hand, the probability P(G∩C) that the student guess the answer and it is correct is:
P(G∩C) = 0.3*0.2 = 0.06
Because, 0.3 is the probability that the student guess the answer and 0.2 is the probability that the answer is correct given that the student guess the answer.
Therefore, The probability P(C) that the answer is correct is:
P(C) = 0.7 + 0.06 = 0.76
Finally, P(K/C) is:
P(K/C) = 0.7/0.76 = 0.9211
Answer:
Step-by-step explanation:
3mn (m+y)
= 3
n + 3mny
Answer:
480,700
Step-by-step explanation:
C(25,7)
25!/(7!*(25-7)!)
15511210043330985984000000/(6402373705728000*5040)
480700
Answer:
3/12 = 1/4
Step-by-step explanation:
There are 12 marbles in the bag. If the marble drawn at random is red, it is one of the 3 red marbles.
The probability is "3 out of 12" = 3/12 which simplifies to 1/4.
