Question

Rhesus factor, is a type of protein found on the outside of red blood cells. The protein is genetically inherited. A donor is said to have Rh+ blood if the Rhesus factor is present in their blood. Suppose that a blood donation campaign is launched by the University of Ottawa walk-in clinic. Among undergraduate students donating blood to walk-in clinic, 30% have Rh+. 1. If seven undergraduate students donate blood at this clinic on a particular day, what is the probability that at least three of them do not have the Rh factor? What is the probability that the number of students with Rh+ blood will be within 0.1 of the true population mean? 2. How many undergraduate students must donate blood to have the probability of at least one Rh+ donor over 0.90?

Answer 1

ho Let 2 p = 0.3 who do not have Rh factos. be the probability that an under graduate student, donating blood to the walk-in-clinic is Rht. Giver 1) If 7 undergraduate students donate blood at this clinic, let x be the number is binomial with parameters D = 7 and i-p Then Х 1-0.3 0.7. :P( at least three do not have Rh factos) = P(x23) 0.7' (1-0.7) 7 2 7-x Ź () 23 0.4712 Let y be the number of students with Rht blood Then Y Nb(7,0.3) binomed distributions het H be the thee population mean. We have to find, P(14-H1 <0.1) CS Scanned with CamScanner

Txo.3 , M = np. 2.1 We have P(14-HI<0-1) = P(-0.124-H 20.1) P(-0.1+2:1<4 <0.1+2.1) = P(2 <Y<2.2) such that, 2. We have to find a = 0.1 = 0.1 = 0.1 P(Y21) = 0.9 P(421) = = 1-0.9 P(4=o) ie; (%) p'(1-P)9-0 We know that p=0.3 (1-0.3)” = 0.1 bog (0.7) = log (0.1) nx(-0.1544) = -1 n n 6.4557 n ~ 6 CS Scanned with CamScanner