Test 2
Age Frequency
6 1
7 2
8 6
9 11
What is the median age?
9
Most graduate schools of business require applicants for admission to take the Graduate Management Admission Council’s GMAT examination. Scores on the GMAT are roughly normally distributed with a mean of 527 and a standard deviation of 112. What is the probability of an individual scoring above 500 on the GMAT?
P(X>=500)=0.5948
Which is an example of negative correlation
A. High levels of employment require employers to offer higher salaries to attract new workers
B. Periods of high unemployment experience falling consumer demand, resulting in downward pressure on prices and inflation.
C. The number of people connected to the Internet has been increasing, and the price of oil has generally trended upward over the same period.
B. Periods of high unemployment experience falling consumer demand, resulting in downward pressure on prices and inflation.
Sam asked 50 people whether they like vegetable pizza or pepperoni pizza.
37 people like vegetable pizza.
25 people like both.
3 people like neither.
Sam picked one of the 50 people at random. Given that the person he chose likes pepperoni pizza, find the probability that they don’t like vegetable pizza.
10/35
A study randomly sampled adults and asked them about their bedtime habits. The data showed that people who drank a cup of tea before bedtime were more likely to go to sleep earlier than those who didn't drink tea.
Which type of study method is this?
Observational study
You're buying trip insurance and car rental insurance
The average cost of trip insurance is $45 with a standard deviation of $3, and the average cost of rental insurance is $15 with a standard deviation of $4.
What is the standard deviation of both combined?
$5
If the histogram interval size is increased, which must remain the same on the new histogram?
Height of the new bars, Shape of the distribution, Widths of teh new bars, Number of bars, Sum of frequencies
Shape of the distribution
The length of human pregnancies from conception to birth approximates a normal distribution with a mean of 266 days and a standard deviation of 16 days. What proportion of all pregnancies will last between 240 and 270 days (roughly between 8 and 9 months)?
0.5471
The correlation coefficient between the number of people connected to the Internet and oil prices is high (r=0.98), as oil prices have generally trended upward over the same period. That means the relationship is linear, but correlation does not mean causation. Is this statement true or false?
False - it may not be linear
The probability that it snows is 0.04. If it snows, the likelihood that school is closed is 0.5. If it doesn't snow, the possibility that school is closed is 0.01. What is the probability that school is closed?
0.04*0.5+0.96*0.01= 0.0296
P(snow)*P(closed|snow) + P(no snow)*P(closed|no snow)
Alma has developed a novel antibiotic. For an antibiotic to be sufficiently effective, it must kill at least 90% of bacteria when applied to a bacterial culture. She used the antibiotic in a Petri dish containing pathogenic bacteria, waited for it to take effect, and then attempted to estimate the percentage of dead bacteria. What type of statistical study did Alma use?
Badly designed experiment
The probability of a man hitting the target is 1/4 with a dart. If he throws the dart 3 times, what is the probability of him hitting the target at least once?
0.578
A sample of 99 distances has a mean of 24 feet and a median of 24.5 feet. Unfortunately, it has just been discovered that an observation which was erroneously recorded as "30" actually had a value of "35." If we make this correction to the data, then
a) The mean remains the same, but the median is increased.
b) the mean and median remain the same.
c) the median remains the same, but the mean is increased.
d) the mean and median are both increased.
e) we do not know how the mean and median are affected without further calculations, but the variance is increased.
c) the median remains the same, but the mean is increased.
A company manufactures lithium-ion batteries, and quality control has determined that the actual time to failure follows a normal distribution. The distribution has a mean operating life of 240 hours and a standard deviation of 3 hours. To be marketed as a "Premium Long-Life" battery, a battery must be in the top 10 percent of all batteries in terms of operating life.
What is the minimum operating life (in hours) a battery must have to be classified as "Premium Long-Life"?
243.84 hours
A least-squares regression line predicts a plant's height (ŷ in cm) based on its age (x in months), given by the equation ŷ=1.2+2.3x
Interpret the y-intercept in the context of this problem.
The predicted height of the plant when it first emerges from the ground is 1.2 cm.
Douglas is going to throw two darts at the bullseye.
The probability of the first throw hitting the bullseye is 0.08.
If the first throw hits, the probability of the second throw hitting is 0.O4.
If the first throw misses, the probability of the second throw hitting is 0.09
What is the likelihood that Douglas hits the bullseye only once?
0.1596
0.96*0.08 + 0.09*0.92
hits the first throw and misses the second + misses the first throw and hits the second
A person who drinks alcohol daily reports that they only drink "sometimes" to avoid judgment from the interviewer because they feel the truth is not a socially acceptable answer.
What is response bias
Harlee uses a device to convert her electronic textbook into Braille. Unfortunately, the textbook did not include text descriptions of the diagrams, and 2\3 of the pages have diagrams. What is the probability of Harlee reading five pages to reach the first page with a diagram? Assume that the probability of each page having a diagram is independent.
(2/3)(1/3)^4 = 0.00823
The outliers in a boxplot are showed as _______ and the widths of the box is____________
stars * and IQR
At a college the scores on the chemistry final exam are approximately normally distributed, with a mean of 75 and a standard deviation of 12. The scores on the calculus final are also approximately normally distributed, with a mean of 80 and a standard deviation of 8. A student scored 81 on the chemistry final and 84 on the calculus final. Relative to the students in each respective class, in which subject did this student do better?
The student did equally well in each course.
A least-squares regression line predicts a plant's height (ŷ in cm) based on its age (x in months), given by the equation ŷ=1.2+2.3x
What is the predicted change in plant growth per year?
2.3*12=27.6
A fair coin will be tossed three times. The set of possible outcomes may be described by the ordered triples{HHH, HHT, HTH,HTT ,THH ,THT ,TTH ,TTT }, where H represents heads and T represents tails.
What is the probability that all three tosses result in heads, given that the three tosses result in more heads than tails?
0.25
4 choices are more heads than tails (HHH, HHT, HTH, THH), then only one of these have ALL heads HHH
Gather 100 adults for a weight loss study. Group them into 50 pairs, matching individuals based on similar age, gender, and starting weight (e.g., two 30-year-old males, two 40-year-old females). Within each pair, randomly assign one person to the new diet (treatment) and the other to the standard diet (control). After 30 days, compare the total weight loss for each person.
This is an example of __________.
matching pair design
Let B be the weight of a single chair with a mean of 40 and a standard deviation of 5. Let X be the weight of a single table with a mean of 70 and a standard deviation of 8. Let W be the total weight of the dining room setup with four chairs and 1 table.
What is the SD of W?
12.81
The mean of a set of data is 35, its median is 33, its standard deviation is 6, and its IQR is 12. A new set is created by first multiplying every term by 5 and then subtracting 10. Which of the following is true?
a) The standard deviation is 20.
b) The sum of the standard deviation and inter quartile range is 18.
c) The mean is 175.
d) The inner quartile range is 50.
e) The difference between the mean and the median is 10.
The difference between the mean and the median is 10.
Suppose the scores for a certain exam are normally distributed with a mean of 80 and a standard deviation of 4. What exam score lies 1.75 standard deviations above the mean?
87
A least-squares regression line predicts a percentage of battery remaining (ŷ) based on phone charge (x in percentage), given by the equation ŷ=1.2-2.3x. Is the correlation coefficient positive or negative?
negative
At a small company, 60 percent of employees are classified as junior-level, and 17 percent work in department A. Of those classified as junior level, 15 percent work in department A. One employee will be selected at random.
What is the probability that the selected employee works in department A and is not classified as junior level?
0.08
P(J and DeptA)= P(J)*P(DeptA|J) = 0.60*0.15=0.09
0.60=P(J)=P(J and DeptA) + P(J and notDeptA)
100 students are randomly assigned to receive either a new math curriculum or the standard curriculum to see if the new curriculum improves test scores. What are the treatment, response variable, and the experiment units?
Treatment: Type of curriculum
Response: The test score
Experimenta Unit: Individual Students
Let B be the weight of a single chair with a mean of 40 and a standard deviation of 5. Let X be the weight of a single table with a mean of 70 and a standard deviation of 8. Let W be the total weight of the dining room setup with four chairs and 1 table.
What is the expected value of W?
230