According to a 2018 survey by Bankrate, 20% of adults in the United States save nothing for retirement (CNBC website). Suppose that twenty-one adults in the United States are selected randomly. What is the probability that more than five of the selected adults save nothing for retirement

0.769296

Step-by-step explanation:

The desired probability can be calculated from binomial probability distribution because there are 21 independent trials and probability of success(saving nothing for retirement) 0.2 remains same for each trial. Here, n=21 and p=0.20. We want to compute P(X>5).

The pdf of binomial distribution is

P(X=x)=nCx(p)^x(1-p)^(n-x)

P(X>5)=1-P(X≤5)

P(X≤5)=P(X=0)+P(X=1)+P(X=2)+P(X=3)+P(X=4)+P(X=5)

P(X=0)=21C0*(0.2)^0*(1-0.2)^(21-0)=0.009223

P(X=1)=21C1*(0.2)^1*(1-0.2)^(21-1)=0.048423

P(X=2)=21C2*(0.2)^2*(1-0.2)^(21-2)=0.121057

P(X=3)=21C3*(0.2)^3*(1-0.2)^(21-3)=0.191673

P(X=4)=21C4*(0.2)^4*(1-0.2)^(21-4)=0.215632

P(X=5)=21C5*(0.2)^5*(1-0.2)^(21-5)=0.183287

P(X≤5)=0.009223+0.048423+0.121057+0.191673+0.215632+0.183287

P(X≤5)=0.769296

P(X≤5) can also be computed by using excel function BINOM.DIST(5,21,0.2,TRUE) which results in

P(X≤5)=0.769296.

saving = more money

step-by-step explanation:

if you have 100 bucks, and you want to buy a candy bar, even if you have one at home, if you choose not to buy it, you save.

~courtney

step-by-step explanation:

de-gf

hj=3x+20

ji=15x-64