Question

Please help and work out :) There are two parts to this problem

A)The scores on an economics examination are normally distributed with a mean of 71 and a standard deviation of 13. If the instructor assigns a grade of A to 13% of the class, what is the lowest score a student may have and still obtain an A?

B)Use the appropriate normal distribution to approximate the resulting binomial distribution.

A basketball player has a 80% chance of making a free throw. (Assume that the throws are independent of each other.) What is the probability of her making 95 or more free throws in 130 trials? (Round your answer to four decimal places.)

Answer 1

A) → 71 Mean - standard deviation – 13 Glade A- 13% need to find x (score) such that P(Xcx) = 0.87 (rather the score which 87% of class scored below) Sece 13 u=71, 2. (x-4) Let 20.87 We need to find x such that: P(2. (x-71)/13) will first find a such that placa) = 0.87 2~1.26 (from standard forms) solve for X : (x-71) 13 x = 1.26 (13) tt) Now, we 1.26 x=87.38 So, the lowest score for student to reciere & still maken be 87.31 an A would b) in mole 130 95 on As throws are independent & p=0.8 9-1-0.8 0.2 teails.. We have tremulae. n-2 P(xzas) - MxP (9) 130-95 (6.1) (0.2) 130 Cas 130! *(0.1) (0.2) (130-95 | 95! 0.0129