Two fair coins are tossed, and the following events are defined:

A: [Observe one head and one tail.]

B: [Observe at least one head.]

a. Define the possible sample points and assign probabilities to each.

b. Draw a Venn diagram for the experiment, showing the sample points and events A and B.

c. Find P(A), P(B) andP(AB).

d. Use the formula for conditional probability to find P (A/B)and P (B/A). Verify your answer by inspecting the Venn diagram and using the concept of reduced sample spaces.

Short Answer

Expert verified

Answer

  1. P (A)= [(H, T), (T, H)],P (B)= [(H, H), (H, T), (T, H)]
  2. Fig.1 Venn diagram
  3. 0.5, 0.75 & 0.5
  4. 0.67, 1.

Step by step solution

01

Step-by-Step SolutionStep 1: Identify the sample points

Probability is the study of prior records or the quantity and kind of probable outcomes to predict an event's result.

Sample points =[(H, H), (H, T), (T, H), (T, T)]P (A)= [(H, T), (T, H)]P (B)= [(H, H), (H, T), (T, H)]

02

Draw a Venn diagram

Here are all the sample points and events of A and B.

03

Find the required probability

P (A) =24=12= 0.5

P (B) =34= 0.75

P (AB) =24=12= 0.5

Hence, the required probabilities are 0.5, 0.75 & 0.5.

04

Find the required probability

P (A/B) =P (AB)P (B)=0.500.75= 0.67

P (B/A) =P (AB)P (A)=0.500.50= 1

Hence, the required probabilities are 0.67, 1.

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Most popular questions from this chapter

Degrees of best-paid CEOs.Refer to the results of the Glassdoor Economic Research (August 25, 2015) survey of the top 40 best-paid CEOs shown in Table 2.1 (p. 65). The data on the highest degree obtained are summarized in the SPSS printout below. Suppose you randomly select five of the CEOs (without replacement) and record the highest degree obtained by each.

a.What is the probability that the highest degree obtained by the first CEO you select is a bachelor’s degree?

b.Suppose the highest degree obtained by each of the first four CEOs you select is a bachelor’s degree. What is the probability that the highest degree obtained

by the fifth CEO you select is a bachelor’s degree?

Scrap rate of machine parts. A press produces parts used in the manufacture of large-screen plasma televisions. If the press is correctly adjusted, it produces parts with a scrap rate of 5%. If it is not adjusted correctly, it produces scrap at a 50% rate. From past company records, the machine is known to be correctly adjusted 90% of the time. A quality-control inspector randomly selects one part from those recently produced by the press and discovers it is defective. What is the probability that the machine is incorrectly adjusted?

Consider the Venn diagram in the next column, where

P(E1)=0.10,P(E2)=0.05,P(E3)=P(E4)=0.2,P(E5)=0.6,P(E6)=0.3,P(E7)=0.06andP(E8)=0.3

Find each of the following probabilities:

a.P(Ac)b.P(Bc)c.P(AcB)d.P(AB)e.P(AB)f.P(AcBc)

g. Are events A and B mutually exclusive? Why?

Reliability of gas station air gauges. Tire and automobile manufacturers and consumer safety experts all recommend that drivers maintain proper tire pressure in their cars. Consequently, many gas stations now provide air pumps and air gauges for their customers. In a Research Note(Nov. 2001), the National Highway Traffic Safety Administration studied the reliability of gas station air gauges. The next table gives the percentage of gas stations that provide air gauges that over-report the pressure level in the tire.

a. If the gas station air pressure gauge reads 35 psi, what is the probability that the pressure is over-reported by 6 psi or more?

b. If the gas station air pressure gauge reads 55 psi, what is the probability that the pressure is over-reported by 8 psi or more?

c. If the gas station air pressure gauge reads 25 psi, what is the probability that the pressure is not over-reported by 4 psi or more?

d. Are the events A= {over report by 4 psi or more} and B= {over report by 6 psi or more} mutually exclusive?

e.Based on your answer to part d, why do the probabilities in the table not sum to 1?

Jamming attacks on wireless networks. Refer to the International Journal of Production Economics (Vol. 172, 2016) study of U.S. military jamming attacks on wireless networks used by terrorists, Exercise 2.8 (p. 73). Recall that 80 recent jamming attacks were classified according to network type (WLAN, WSN, or AHN) attacked and the network's number of channels (single- or multi-channel). The results are reproduced in the accompanying table.

a. Find the probability that a recent jamming attack involved a single-channel network.

b. Find the probability that a recent jamming attack involved a WLAN network.


Network Type/Number of Channels

Number of Jamming Attacks

WLAN / Single

31

WSN / Single

13

AHN / Single

8

WLAN / Multi

14

WSN / Multi

9

AHN / Multi

5

TOTAL

80

Source: S. Vadlamani et al., "Jamming Attacks on Wireless Networks: A Taxonomic Survey, "International Journal of Production Economics, Vol. 172, 2016 (Figure 6)

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