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3 years ago

A person read that the average number of hours an adult sleeps on Friday night to Saturday morning was 7.2 hours. The

Mathematics

1 answer:

Elan Coil [88]3 years ago

7 0

Calculate the value of z and its probability, since with this we can know how likely it is that this will happen.

We have that the mean (m) is equal to 8.3, the standard deviation (sd) 1.2 and the sample size (n) = 15

They ask us for P (x =7.2)

For this, the first thing is to calculate z, which is given by the following equation:

z = (x - m) / (sd / (n ^ 1/2))

We have all these values, replacing we have:

z = (7.2 - 8.3) / (1.2 / (15 ^ (1/2))

z = -3.55

With the normal distribution table (attached), we have that at that value the approximate probability is:

P (z = -3.55) = 0.0001

The probability is 0.01 %

This affirms that the students do not sleep what the study says because the probability of this happening according to the survey is almost nil.

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There are 5 exams in a semester. You have scored 77, 90, 85, and 100 on the previous four exams. What must you make on the fifth

siniylev [52]

Answer:

<h2>The correct answer for this question is 78.</h2>

Step-by-step explanation:

The average or mean of any variable or mathematical phenomenon is calculated as the division of the sum of all the numbers or items within the particular variable by the total number of items or numbers within the variable.
In this case, the marks of the 4 exams in the semester are 77,90,85 and 100 respectively.There are total 5 exams in the semester.
Let's suppose that the marks for the 5th exam is x.
Therefore, based on the mathematical formula to compute average or mean,to get an overall average of 86 including all the 5 exams, one has to get:-

$\frac{77+90+85+100+x}{5}=86$

$77+90+85+100+x=430$

$x=430-77-90-85-100$

$x=78$

Hence, based on the above calculations,one has has to get 78 on the 5th exam to obtain an overall average of exactly 86.

5 0

4 years ago

After 6 days, the mass m, in grams, of

juin [17]

Answer:

123445

Step-by-step explanation:

125123254125

3 0

3 years ago

Read 2 more answers

Use the quadratic formula to find the solutions for..<br> y = 2x^2 - 9x + 5.

Yakvenalex [24]

Answer: $x=\frac{9}{4}-\frac{\sqrt{41} }{4} \\x=\frac{9}{4}+\frac{\sqrt{41} }{4}$

Step-by-step explanation:

$2x^2-9x+5$

a=2

b=-9

c=5

$x=\frac{-b\frac{+}{}\sqrt{b^2-4ac} }{2a}$

$x=\frac{-(-9)\frac{+}{}\sqrt{(-9)^2-4(2)(5)} }{2(2)}$

$x=\frac{9\frac{+}{}\sqrt{81-40} }{4}$

$x=\frac{9\frac{+}{}\sqrt{41} }{4}$

$x=\frac{9}{4}-\frac{\sqrt{41} }{4} \\x=\frac{9}{4}+\frac{\sqrt{41} }{4}$

4 0

3 years ago

A study found that a 95% confidence interval for the mean μ of a particular population was computed from a random sample of 1200

kotykmax [81]

Answer:

95% confidence interval for the mean μ is (6,14)

The Population mean μ lies between ( 6, 14 )

Step-by-step explanation:

<u><em>Explanation</em></u>:-

Given random sample 'n' = 1200

95% confidence interval for the mean μ is determined by

$(x^{-} -Z_{\alpha } \frac{S.D}{\sqrt{n} } , x^{-} +Z_{\alpha } \frac{S.D}{\sqrt{n} } )$

Level of significance = 95% 0r 0.05

Z₀.₀₅ = 1.96

$(x^{-} -Z_{\alpha } \frac{S.D}{\sqrt{n} } , x^{-} +Z_{\alpha } \frac{S.D}{\sqrt{n} } )$ = 10 ± 4

Mean of the small sample = 10

95% of confidence intervals are

( 10 ±4 )

( 10 -4 , 10+4)

( 6 , 14 )

95% confidence interval for the mean μ lies between ( 6, 14 )

8 0

3 years ago

Why do whole numbers raised to an exponent get greater well fractions raised to an exponent get smaller

adelina 88 [10]

Because when you raise an exponent on a fraction, it is basically dividing into itself. Imagine 1/3 multiplied my 3 (Ans is 1), the fractions aren't whole numbers so when they multiply into another number, it uses division

4 0

3 years ago