<span>0.3278
Use combination formula ((20C4)*(15C3))/(35C7) = 0.3278
20C4 - combinations of 4 females from 20
15C3 - combinations of 3 males from 15
35C7 - all possible combinations of 7 students from 35 students in total</span>
Answer:
yes
Step-by-step explanation:
Answer:
Step-by-step explanation:
Given that 30% of all students who have to buy a text for a particular course want a new copy (the successes!), whereas the other 70% want a used copy.
Each purchaser is independent of the other and there are only two outcomes
X - no of persons who prefer new copies is Bin (15, 0.3)
a) E(x) = np =![15(0.3) =4.5](https://tex.z-dn.net/?f=15%280.3%29%20%3D4.5)
Var(x) = npq = ![4.5*0.7\\=3.15](https://tex.z-dn.net/?f=4.5%2A0.7%5C%5C%3D3.15)
Std dev (x) = 1.775
b)![P(X>4.5+2(1.775)\\= P(X>8.050)\\= P(9)+P(10)+...+P(15)\\= 1-F(8)\\= 0.0152](https://tex.z-dn.net/?f=P%28X%3E4.5%2B2%281.775%29%5C%5C%3D%20P%28X%3E8.050%29%5C%5C%3D%20P%289%29%2BP%2810%29%2B...%2BP%2815%29%5C%5C%3D%201-F%288%29%5C%5C%3D%200.0152)
c) ![P(X\leq 10)\\=F(10)\\=0.9993](https://tex.z-dn.net/?f=P%28X%5Cleq%2010%29%5C%5C%3DF%2810%29%5C%5C%3D0.9993)
d) h(X) = revenue when x of 15 purchasers want new copies
E(h(x)) = 100(E(x) = 450
Here h(x) = 100x
Hence E(100x) = 100E(X)
Answer:
1000
Step-by-step explanation: