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11Alexandr11 [23.1K]
2 years ago
8

A fourth-grade teacher gives homework every night in both mathematics and language arts. the time to complete the mathematics ho

mework has a mean of 10 minutes and a standard deviation of 3 minutes. the time to complete the language arts assignment has a mean of 12 minutes and a standard deviation of 4 minutes. assuming the times to complete homework assignments in math and language arts are independent, the standard deviation of the time required to complete the entire homework assignment is
Mathematics
2 answers:
xz_007 [3.2K]2 years ago
7 0
The standard deviation for the combined assignment is 5 minutes.

To combine the standard deviations, we use:

\sigma_z=\sqrt{(\sigma_x)^2+(\sigma_y)^2}

With our information, we have:
\sigma_z=\sqrt{3^2+4^2}
\\
\\=\sqrt{9+16}=\sqrt{25}=5
slega [8]2 years ago
7 0

Answer:

5 min

Step-by-step explanation:

The combine standard deviation, SDf, of two independent variables having standard deviation, SD1 and SD2, is given by:

SDf² = SD1² + SD2²

SDf²= 3² + 4²

SDf= 5

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How much water is in an empty glass that is 10cm high and has a diameter of 5cm
Lilit [14]

Answer:

How much water is in an empty glass that is 10cm high and has a diameter of 5 cm ?

= 196,25 cm

Step-by-step explanation:

diameter = 5 cm

radius = 1/2 × diameter

radius = 1/2 × 5 = 2,5

How much water is in an empty glass that is 10cm high and has a diameter of 5 cm?

= π × r × r × high

= 3,14 × 2,5 × 2,5 × 10

= 196,25 cm

4 0
2 years ago
The percentage of U.S. college freshmen claiming no religious affiliation has risen in recent decades. The bar graph shows the
emmainna [20.7K]

Answer:

0.5%/year

24.2%

Step-by-step explanation:

Estimate the average yearly increase in the percentage of first-year college females claiming no religious affiliation

Percentage of females by year:

1980 = 6.2%

1990 = 10.8%

2000 = 13.6%

2012 = 21.7%

Average yearly increase :

Percentage increase between 1980 - 2012 :

2012% - 1980% = ( 21.7% - 6.2%) = 15.5% increase over [(2012 - 1980)] = 32 years

15.5 % / 32 years = 0.484375% / year = 0.5%/year

b. Estimate the percentage of first-year college females who will claim no religious affiliation in 2030,

Given an average increase of 0.484375% / year

(2030 - 1980) = 50 years

Hence by 2030 ; ( 50 years × 0.484375%/year) = 24.218% will claim no religious affiliation.

=24.2% (nearest tenth)

3 0
2 years ago
Sten sat on a bench and read a book while Manu was at soccer practice. He read for 35 minutes and stopped at 6:10 p.m.
Dahasolnce [82]

Answer:

5:35

Step-by-step explanation:

6 0
2 years ago
If PQ=RS, which of the following must be true?
maw [93]

<u>Answer:</u>

If PQ=RS then PQ and RS have the same length. Hence option D is correct

<u>Solution:</u>

Given that, pq = rs  

And, we have to find which of the given options are true.

<u><em>a) pq and rs form a straight angle </em></u>

We can’t decide the angle in between pq and rs just by the statement pq = rs.

So this statement is false.

<u><em>b) pq and rs form a zero angle. </em></u>

We can’t decide the angle in between pq and rs just by the statement pq = rs.

So this statement is false.

<u><em>c) pq and rs are same segment. </em></u>

If two things equal then there is no condition that both represents a single item.

So this statement is false.

<u><em>d) pq and rs have the same length </em></u>

As given that pq = rs, we can say that they will have the same length  

Hence, option d is true.

4 0
2 years ago
A quality control engineer tests the quality of produced computers. suppose that 5% of computers have defects, and defects occur
11111nata11111 [884]
(a) 0.059582148 probability of exactly 3 defective out of 20

 (b) 0.98598125 probability that at least 5 need to be tested to find 2 defective.

  (a) For exactly 3 defective computers, we need to find the calculate the probability of 3 defective computers with 17 good computers, and then multiply by the number of ways we could arrange those computers. So

 0.05^3 * (1 - 0.05)^(20-3) * 20! / (3!(20-3)!)

 = 0.05^3 * 0.95^17 * 20! / (3!17!)

 = 0.05^3 * 0.95^17 * 20*19*18*17! / (3!17!)

 = 0.05^3 * 0.95^17 * 20*19*18 / (1*2*3)

 = 0.05^3 * 0.95^17 * 20*19*(2*3*3) / (2*3)

 = 0.05^3 * 0.95^17 * 20*19*3

 = 0.000125* 0.418120335 * 1140

 = 0.059582148

  (b) For this problem, let's recast the problem into "What's the probability of having only 0 or 1 defective computers out of 4?" After all, if at most 1 defective computers have been found, then a fifth computer would need to be tested in order to attempt to find another defective computer. So the probability of getting 0 defective computers out of 4 is (1-0.05)^4 = 0.95^4 = 0.81450625.

 The probability of getting exactly 1 defective computer out of 4 is 0.05*(1-0.05)^3*4!/(1!(4-1)!)

 = 0.05*0.95^3*24/(1!3!)

 = 0.05*0.857375*24/6

 = 0.171475

 
 So the probability of getting only 0 or 1 defective computers out of the 1st 4 is 0.81450625 + 0.171475 = 0.98598125 which is also the probability that at least 5 computers need to be tested.
3 0
2 years ago
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