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
Mazyrski [523]
3 years ago
11

An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to make an est

imate at the 90% level of confidence. For a sample of 837 third graders, the mean words per minute read was 24.9. Assume a population standard deviation of 5.1. Construct the confidence interval for the mean number of words a third grader can read per minute. Round your answers to one decimal place.

Mathematics
2 answers:
brilliants [131]3 years ago
7 0

Answer: (24.6 , 25.2)

Step-by-step explanation:

Formula to find the confidence interval for population mean (\mu) is given by :-

\overline{x}\pm z^*\dfrac{\sigma}{\sqrt{n}}.

, where \overline{x} = Sample mean

z* = Critical z-value. (By z-table)

\sigma = Population standard deviation.

n= Sample size.

As per given , we have

\overline{x}=24.9

\sigma=5.1

n= 837

The critical value for 90% confidence interval : z* = 1.645 (By z-table)

The confidence interval for the mean number of words a third grader can read per minute will be :

24.9\pm (1.645)\dfrac{5.1}{\sqrt{837}}\\\\ 24.9\pm (1.645)(0.176281788104)\\\\=24.9\pm0.289983541431\\\\\approx24.9\pm0.3\\\\=(24.9-0.3,\ 24.9+0.3)\\\\=(24.6,\ 25.2)

∴  The confidence interval for the mean number of words a third grader can read per minute= (24.6 , 25.2)

Serga [27]3 years ago
4 0

Answer:we are 90% confident that

the mean number of words a third grader can read per minute is between 24 and 25

Step-by-step explanation:

Sample size n=837

Sample mean x bar= 24.9

Standard deviation , sigma= 5.1

And the formulae;

See attached picture for the solution.

You might be interested in
A local bank needs information concerning the savings account balances of its customers. A random sample of 15 accounts was chec
PSYCHO15rus [73]

Answer:

(513.14, 860.36) is a 98% confidence interval for the true mean

Step-by-step explanation:

We have a small sample size of n = 15, the mean balance was \bar{x} = 686.75 with a standard deviation of s = 256.20. The confidence interval is given by \bar{x}\pm t_{\alpha/2}(\frac{s}{\sqrt{n}}) where t_{\alpha/2} is the 100(\alpha/2)th quantile of the t distribution with n-1=15-1=14 degrees of freedom. As we want a 100(1-\alpha)% = 98% confidence interval, we have that \alpha = 0.02 and the confidence interval is 686.75\pm t_{0.01}(\frac{256.20}{\sqrt{15}}) where t_{0.01} is the 1st quantile of the t distribution with 14 df, i.e., t_{0.01} = -2.6245. Then, we have 686.75\pm (-2.6245)(\frac{256.20}{\sqrt{15}}) and the 98% confidence interval is given by (513.1379, 860.3621)

7 0
4 years ago
7 yards 2 feet = ____ feet ( please include an explanation when answering, I need to get an understanding of it )
ELEN [110]
7 yds 2 ft = _____ ft

1 yd = 3 ft...so 7 yds = (3 * 7) = 21 ft.......21 ft + 2 ft = 23 ft

so 7 yds 2 ft = 23 ft <==
4 0
3 years ago
Read 2 more answers
Help me help me please I have to finish this by Tommrow
ira [324]

A.

i did this test already trust me

5 0
3 years ago
Read 2 more answers
What is the equation in point−slope form of the line passing through (0, 6) and (1, 3)?
Leya [2.2K]
(0,6)(1,3)
slope(m) = (3 - 6) / (1 - 0) = -3

y - y1 = m(x - x1)
slope(m) = -3
(1,3)...x1 = 1 and y1 = 3
now we sub
y - 3 = -3(x - 1) <===
5 0
4 years ago
29. A painter leans a ladder against the side of a
Lerok [7]

Answer:

16.3 feet (to the nearest tenth)

Step-by-step explanation:

Use Pythagoras theorem

Length = sqrt(3^2+16^2) = sqrt(9+256) = sqrt(265) = 16.3 ft.

5 0
4 years ago
Read 2 more answers
Other questions:
  • An open-top bin is to be made from a 15-centimeter by 40-centimeter piece of plastic by removing a square from each corner of th
    10·1 answer
  • A boat whose speed in 15km/hr in still water goes 30 km downstream and come back in a total of 4 hours 30 minutes.The speed of t
    11·2 answers
  • If the volume of the pyramid shown is 216 inches cubed, what is the area of its base?
    8·2 answers
  • What is the solution of 16x-8x-12=24+20
    12·2 answers
  • Jeff has a hot dog stand on the beach. He charges $3.50 for a hamburger (x) and $2 for a hot dog (y). His goal is to make at lea
    9·1 answer
  • Algebra Graph each line.<br> y = 3x + 4
    8·1 answer
  • *10 POINTS*
    9·1 answer
  • 9. Tiana has 60 tokens to play games at the arcade. Each game costs 4 coins, and
    5·1 answer
  • Six friends attend a matinee movie and spend $9 per ticket. They also purchase a small bag of popcorn, p, each. If the friends s
    6·1 answer
  • Is the given question a statistical question? Explain. (NOT A MULTIPLE CHOICE)
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!