BUS300 Midterm

the time to fly between new york city and chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. what is the mean?

(150+120)/2 =135

when applying the special rule of addition for mutually exclusive events, the joint probability is

0

chances are 50-50 that a newborn baby will be a girl. for families with 5 children, what is the probability that all the children are girls?

0.5 = girl 0.5^5=0.031

the average weight of a group of 30 friends increases by 1 kg when the weight of their football coach was added. if average weight of the group after including the weight of the football coach is 31 kg, what is the weight of their football coach?

1) 30 friends*30kg=900 --> (900+c)/(30+1)=31kg, c=61

a sample of the monthly amounts spent for food by families of four receiving food stamps approximates a symmetrical distribution. the sample mean is $150 and the standard deviation is $20. using the empirical rule, about 95% of the monthly food expenditures are between what two amounts?

1) draw graph with the mean & std. dev 2) std dev 1 = 68%, 2= 95%, 3=99.97%

the weight of cans of fruit is normally distributed with a mean of 1000 grams and a standard deviation of 50. what percent of the cans weigh 860 grams or less?

1) find Z: (x-mean)/std dev --> (860-1000)/50= 2.8 2) look at the normal distribution graph answer: 0.0026

a company is studying the number of monthly absences among its 125 employees. the following probability distribution shows the likelihood that people were absent 0,1,2,3,4,5 days last month. what is the variance of the number of days absent?

1) multiply x (the # of days absent) and p(x) (probability) to get the xP(x) row 2) variance x^2*p(x) 3) take the totals of both rows and add them, subtract variance from xP(x) total

in a management trainee program, 80% of the trainees are female, 20% male. 90% of the females attended college, 78% of the males attended college. a trainee is randomly selected. what is the probability that the person selected is a female and did NOT attend college?

10% of the females didn't attend college 0.8 females * 0.1 = 0.08% female and didn't go to college

the weights of a sample crates ready for shipment to Moscow, Russia are #,#,#. what is the mean deviation?

102 (mean of the numbers given) | |+1 =103 | |+4=106 | 101=-1| |+1=103 97=-5| (-5+-1+1+4+1)/5 = 2.4 **absolute value of neg #'s

refer to the following distribution of commissions. what is the relative frequency for those salespersons that earn from $1600 to $1800?

1600-1800 class frequency amount/add the total of class frequencies

production of passenger cars in japan increased from 3.94 million in 1999 to 6.74 million in 2009. what is the geometric mean annual percent increase

2009-1999=10 10sqroot (6.74/3.94) =0.0551

a sales representative calls on 4 hospitals in west chester county. it is immaterial what order he calls on them. how many ways can he organize his calls?

4! = 24

for a binomial distribution, the mean is 4.0 and n=8. what is pi for this distribution?

4/8=0.5

affirmative action commitments by many organizations have led to an increase in the number of women in executive positions. satellite office systems has vacancies for two executives that it will fill from among four women and six men. whats the probability that no woman is selected?

4C10 * 6C2 =1/3 10C2

a builder has agreed not to build all look alike homes in a new subdivision. the builder has 3 different interior plans that can be combined with any of the 5 different home exteriors. how many homes can be built

5*3=15

refer to the following information from a frequency distribution for "heights of college women" recorded to the nearest inch. The first two class midpoints are 62.5 and 65.5. what are the class limits for the 3rd class?

65.5-62.5=3, go through the ABCD, find the mean of the two numbers, and then subtract the higher mean from it. mean= 68.5-65.5=3

a gumball machine has just been filled with 50 black, 150 white, 100 red, and 100 yellow gum balls that have been thoroughly mixed. sue and jim both purchased one gumball. what is the likelihood both sue and jim get red gumballs?

N = 400, P(R1 & R2) 100/400 = 0.25 99/399 = 0.2481 0.25*0.2481 = 0.062

a new extended-life lightbulb has an average service life of 750 hours with a standard deviation of 50 hours. if the service life of these light bulbs approximates a normal distribution, about what percent of the distribution will be between 600 hours and 900 hours?

P(600<x<900) N=750 (600-750)/50=-3 (107-750)/50=3 graph: .9987-.0013=0.9974 99.7%

a firm offers routine physical examinations as part of a health service program for its employees. the exams showed that 8% of the employees needed corrective shoes, 15% needed major dental work, and 3% needed both corrective shoes and major dental work. what is the probability that an employee selected at random will need either corrective shoes or major dental work?

P(S or D)=P(S)+P(D)-P(S&D) 0.2 =0.08+0.15-0.03

a study by the national park service revealed that 50% of the vacationers going to the rocky mountain region visit yellowstone park, 40% visit the grand tetons, and 35% visit both. whats the probability that a vacationer will visit either of these attractions?

P(Y or T) = P(Y)+P(T)-P(Y & T) 0.55 = 0.5 + 0.4 - 0.35

the time to fly between new york city and chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. what is the probability that a flight is more than 140 minutes?

[1/(min-max)]* (max-min)

refer to the following frequency distribution on days absent during a calendar year y employees of a manufacturing company. how many employees were absent 6+ days?

add 6-9 class, 9-12 class, and 12-15 class = 22

the probabilities and the number of automobiles lined up at a lakeside olds at opening time for service are: number * probability = xP(x) 1 0.05 2 .3 3 .4 4 .25 on a typical day, how many automobiles should lakeside olds expect to be lined up at opening?

add the xP(x) column .05+0.6+1.2+1 = 2.85

each salesperson in a large department store chain is rated on their sales ability and their potential for advancement. the data for the 500 sampled salespeople are summarized in the following table. What is the probability that a salesperson selected at random will have below average sales ability and fair potential for advancement?

fair total below average 16 total 500 16/500 = 0.032

a sample of single persons receiving social security payments revealed these monthly benefits #,#,#. how many observations are below the median?

find the median, count how many are below

consider the result of a fictional stat100 final exam taken by 120 students, as given in the following relative frequency distribution. how many students received at least a 70 on the exam?

grade 70-79 (25%) grade 80-89 (15% grade 90-100 (5%) 120*.25 + 120*.15 + 120*.05 = 54

the monthly salaries of a sample of 100 employees were rounded to the nearest $10. They ranged from $1040 to $1720. If we want to condense the data into 7 classes, what is the most convenient class interval?

high i= ------ low

what is the area under the normal curve between z=-1.0 and z=-2.0

look at the graph at 1.0 and 2.0. subtract!

the mean, as a measure of central location would be inappropriate for which one of the following?

marital status of college students at a particular university

15 accounting majors had an average grade of 90 on a finance exam. 7 marketing majors averaged 85, while 10 finance majors averaged 93 on the same exam. what is the weighted mean for the 32 students taking the exam?

n=15+10+7=32 total {(15*90)+(7*85)+(10*93)}/32 = 89.84

a bank asks customers to evaluate the drive-thru service as good, average, or poor. which level of measurement is this classification?

ordinal

the mean amount spent by a family of four on food per month is $500 with a standard deviation of $75. assuming that the food costs are normally distributed, what is the probability that a family spends less than $410 per month?

p (x-mean) (410-500) ------------------------ = -1.2 = 0.1151 std dev (75) mean: 500, std dev: 75, x=410

a group of employees of Unique Services will be surveyed about a new pension plan. In-depth interviews with each employee selected in the sample will be conducted. what is the probability that the first person selected is either in maintenance or in secretarial?

p(maintenance) = 50 maintenance/total = 0.025 + 68 secretarial/total) = 0.059

sixty percent of the customers of a fast food chain order a hamburger, french fries, and a drink. i fa random sample of 15 cash register receipts is selected, what is the probability that 10 or more will show that the above three food items were ordered? (Refer to the binomial table for finding the probabilities)

p(x) =nCx*pi^x (1-pi)^(n-x) n = 15 p= 0.6 add all of the probabilities that are over 10

if the variance of the "number of daily parking tickets issued" is 100, the variance is defined as

the number of daily parking tickets squared

a study of interior designers' opinions with respect to the most desirable primary color executive offices. what is the probability that a designer does not prefer yellow?

total 400 p(not yellow) = 1-p(yellow) 0.885 = 1- (46/400)

a bottling company offers three kinds of delivery service- instant, same day, and within five days. the profit per delivery varies according to the kind of delivery. the profit for an instant delivery is less than the other kinds because the driver has to go directly to a grocery store with a small load and return to the bottling plant. to find out what effect each type of delivery has on the profit picture,e the company summarized the data in the following table based on deliveries for the previous quarter. what is the weighted mean profit per delivery?

{(100*70)+(60*100)+(40*160)}/100+60+40= $97