1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
ivann1987 [24]
2 years ago
12

The Office of Student Services at a large western state university maintains information on the study habits of its full-time st

udents. Their studies indicate that the mean amount of time undergraduate students study per week is 20 hours. The hours studied follows the normal distribution with a population standard deviation of seven hours. Suppose we select a random sample of 125 current students. What is the probability that the mean of this sample is between 19.25 hours and 21.0 hours
Mathematics
1 answer:
ExtremeBDS [4]2 years ago
8 0

There is a probability of 77% that the mean of this sample is between 19.25 hours and 21.0 hours

Z score is used to determine by how many standard deviations the raw score is above or below the mean. The z score is given by:

z=\frac{x-\mu}{\sigma/\sqrt{n} } \\\\where\ x=raw\ score,\mu=mean,\sigma=standard\ deviation,n=sample\ size

Given that μ = 20, σ = 7, n = 125.

For x = 19.25:

z=\frac{19.25-20}{7/\sqrt{125} } =-1.20\\\\\\For\ x=21:\\\\z=\frac{21-20}{7/\sqrt{125} } =0.62

From the normal distribution table, P(-1.20 < z < 0.62) = P(z < 0.62) - P(z < -1.2) = 0.8849 - 0.1151 = 0.7698 = 77%

There is a probability of 77% that the mean of this sample is between 19.25 hours and 21.0 hours

Find out more on z score at: brainly.com/question/25638875

You might be interested in
What is the probability that a couple will have a girl a boy a girl and a boy in this specific order?
olga_2 [115]
P(boy)=1/2
P(girl)=1/2
P(a girl, a boy , a girl and a boy)=1/2*1/2*1/2*1/2= 1/16
P(2 boys and 2 girls ) = 1/[4!/(2!*2!)] =1/6

hope this helps u

3 0
3 years ago
In still water Kevin and Virginia can paddle a canoe at 12mph.It takes them a total of 6hours to paddle 32 miles up a river and
denpristay [2]
Let c represent the speed of the current.

time = distance/speed

Upriver, the current is subtracted from the canoe speed; downriver, it adds.
  6 = 32/(12 -c) +32/(12 +c)
  6(12² -c²) = 32(12 +c) +32(12 -c) . . . . . multiply by (12 +c)(12 -c)
  0 = 6c² -96 . . . . . . . . . . . . . . . . . . . . . . subtract the left side
  96/6 = c² . . . . . . . . . . . . . . . . . . . . . . . . add 96, divide by 6
  4 = c . . . . . . . . . . . . . . . . . . . . . . . . . . . . take the square root

The rate of the current is 4 mph.
4 0
3 years ago
Ann and Ruth bowled together and had a combined score of 410 points. Ann's score was 44 points less than Ruth's score. Write a s
masha68 [24]

Answer:

x=y-44 and x+y=410

Step-by-step explanation:

So, you want to use the equations x=y-44 and  x+y=410 when x is Ann's score and y is Ruth's score. This is because x (Ann's score) is Ruth's score (y) but 44 less, so you subtract y-44 to get x. Then x+y would also have to equal 410 so that's the other equation. Graphing the 2 equations gets you to the point  (183,227) in which Ann's score is 183 points and Ruth's score is 227 points.

3 0
3 years ago
You have a 12 foot ladder and need to reach exactly 9 feet up the wall. How far away from the wall should you place the ladder s
dusya [7]
Pythagorean thoerem
we imagine the wall as a leg of a right triangle, the ladder is the hypotonuse and the distance from the bottom of the ladder to the wall is the other leg

so if we have a right triangle with leg length a and b and hypotnuse length c then
a²+b²=c²

so
given that one of the legs is 9ft (9 ft is the height of the triangle)
and the hypotnuse is 12 ft (length of ladder)
then say the last leg is x

so
x²+9²=12²
x²+81=144
mius 81 both sides
x²=63
sqrt both sides
x=√63
x=3√7

you should place it 3√7ft or about 7.9 or 8ft away

4 0
3 years ago
How would to show a rate of change of 60 miles per hour on a graph
Fudgin [204]
I think the answer is 12
3 0
3 years ago
Other questions:
  • What is 5/8 divided by 1/4 ?
    11·2 answers
  • The manager at a movie theater collects data on comedy and action movie attendance to
    15·1 answer
  • How do businesses help a country’s economy?
    12·2 answers
  • Write an equation of a line that has an undefined slope and goes through the point (9,-5)
    6·2 answers
  • What is the slope of a line that is parallel to the line whose equation is ax+by=c?
    11·2 answers
  • Name 3 things that you need to know to know somethings volume. (teacher didn’t say what)
    6·1 answer
  • PLEASE HELP ME NOT THAT HARD I THINK
    13·2 answers
  • If JKLM is a trapezoid, which statement must be true?
    13·1 answer
  • Need help don’t know what to do I’m confused
    11·1 answer
  • Kara wants to make a histogram of the number of students who wear blue shirts in her class throughout the week. She gathered the
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!