Question
Question #5 ASAP PLEASE!
individuals will suffer a bad reaction. 2. (20 points) probability that in a succesive tosses of a fair die, a 4 will come up for the first time on the 5th toss (b) Find the probability that in a succesive tosses of a fair die, a 4 will come up for the 3rd time on the 5th toss. 3. (25 points) A fair coin is tossed 500 times. Find the probability that the number of tails will not differ from 250 by more than 30 4. (20 points) Find the area under the normal curve (a) to the left of z 1.78, (b) corresponding to 0.80 s z s 1.53 5. (10 points) The mean grade of a final examination was 72, and the stan- dard deviation was 9. The top 10 of the students will receive A's. What is the minimum grade a student must get in order to receive an A?
Explanation / Answer
5. Mean = 72
standard deviation = 9
P(X > A) = 10% = 0.1
P(X <A) = 1-0.1 = 0.9
P(Z < (A - mean)/standard deviation) = 0.9
P(Z < (A - 72)/9) = 0.9
From standard normal distribution table, the z value corresponding to probability of 0.9 is 1.28
S0,
(A - 72)/9 = 1.28
A = 83.52
So, the minimum grade a student must get in order to receive an A is 83.52