A teacher asks 25 of her students to write down their favorite color. The result

Question

A teacher asks 25 of her students to write down their favorite color. The results are presented below: 4. Color frequency Red 8 Blue 12 Green 5 If a student is selected at random from the above group of 25, what is the probability that this student likes the red color? Grade frequency 1 50 230 340 4 42 5 38 6 50 if a student is selected at random from this school, what is the probability that this student is in fourth grade? Chris Paul of the Los Angeles Lakers had a free throw percentage of 90% in the 2014-15 regular season. If he has 20 free throw attempts, what is the probability he will make all 20? 6. In a clinical trial, researcher found that a certain drug had a 8% chance of curing a known disease. if 15 people are known to have the disease what is the probability of at least 2 being cured?

Explanation / Answer

Question 4

Pr(A random student like red color) = 8/25 = 0.32

Question 5

Total students = 50 + 30 + 40 + 42 + 38 + 50 = 250

Pr(A random student is in fourth grade) = 42/250 = 0.168

Question 6

Here the distribution is binomial where n = 20 and p = 0.90

Pr(X = 20 ; 20 ; 0.90) = 20C0 (0.90)20 = 0.122

Question 7

Here n = 15 and p = 0.08

Pr(x >=2 ; 15; 0.08) = 1 - [Pr(X = 0) + Pr(x = 1)]

Pr(x = 0) = 15C0 (0.08)0 (0.92)15   = 0.2863

Pr(x = 1) = 15C1 (0.08)1(0.92)14 = 0.3734

Pr(x >=2 ; 15; 0.08) = 1 - [Pr(X = 0) + Pr(x = 1)] = 1- (0.2863 + 0.3734) = 0.6597

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