Question

A recent study of 500 American males aged 18-21 found that 237 had 1 ticket in the past year, 112 had 2 tickets in the past year, 17 had 3 tickets in the past year, 5 had 4 tickets in the past year, and 1 had 5 tickets in the past year. The rest of the men did not have any tickets in the past year. What is the expected number of tickets an 18-21-year-old American male will have in one year?

Answer 1

Answer:

The expected number of tickets is 1.273

Step-by-step explanation:

Expected Value of a Discrete Probability Distribution

Given a discrete distribution with values

x={x1,x2,x3,...,xn}

And respective probabilities

p={p1,p2,p3,...pn}

The expected value EX of the entire distribution is

$EX=\sum_{i}x_i.p_i$

The recent study of American males provides an approximate distribution of probabilities based on the number of tickets they had past year, according to the following data:

237 had 1 ticket

112 had 2 tickets

17 had 3 tickets

5 had 4 tickets

1 had 5 tickets

The total number of tickets is 237+112+17+5+1=372

Taking the number of tickets as the independent variable, then

x={1,2,3,4,5}

Each probability can be found as the relative frequency of the number of tickets as follows:

$\displaystyle p_1=\frac{237}{372}=0.637$

$\displaystyle p_2=\frac{112}{372}=0.301$

$\displaystyle p_1=\frac{17}{372}=0.046$

$\displaystyle p_1=\frac{5}{372}=0.013$

$\displaystyle p_1=\frac{1}{372}=0.003$

Therefore

p={0.637,0.301,0.046,0.013,0.003}

Compute EX

$EX=1*0.637+2*0.301+3*0.046+4*0.013+5*0.003$

$\boxed{EX=1.273}$

The expected number of tickets is 1.273