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Eduardwww [97]
2 years ago
6

A nationwide survey of 100 boys and 50 girls in the first grade found that the daily average number of boys who are absent from

school is 15, with a standard deviation of 7. For girls, the average number of absentees is 10, with a standard deviation of 6. The standard deviation of the difference is
Mathematics
2 answers:
dusya [7]2 years ago
6 0
Te difference of 2 standard deviation of a population n1 & n2 is given by the formula:
sigma (difference)=√(sigma1/n1 + sigma2/n2), Plug:

sigma(d)= √(49/100 + 36/50)

Sigma(d=difference) =1.1

Gala2k [10]2 years ago
5 0

Find the mean difference (male absences minus female absences) in the population.

μd = μ1 - μ2 = 15 - 10 = 5

Find the standard deviation of the difference.

σd = sqrt( σ12 / n1 + σ22 / n2 )

σd = sqrt(72/100 + 62/50) = sqrt(49/100 + 36/50) = sqrt(0.49 + .72) = sqrt(1.21) = 1.1

Find the z-score that produced when boys have three more days of absences than girls. When boys have three more days of absences, the number of male absences minus female absences is three. And the associated z-score is

z = (x - μ)/σ = (3 - 5)/1.1 = -2/1.1 = -1.818

Find the probability. This problem requires us to find the probability that the average number of absences in the boy sample minus the average number of absences in the girl sample is less than 3. To find this probability, we enter the z-score (-1.818) into Stat Trek's Normal Distribution Calculator. We find that the probability of a z-score being -1.818 or less is about 0.035


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Jose must plant 380 trees. In the past 7 days Jose planted 266 trees. If he continues at this rate, how many more days will it t
Sonja [21]

Answer:

16 days

Step-by-step explanation:

because

380-266=114

114 divided by 7= 16

3 0
2 years ago
G = x-c/x solve for x
Elan Coil [88]

Answer:

x=\frac{c}{1-g}

Step-by-step explanation:

Step 1: Multiply both sides by x,

 gx=−c+x

Step 2: Add -x to both sides.

gx+−x=−c+x+−x

gx−x=−c

Step 3: Factor out variable x.

x(g−1)=−c

Step 4: Divide both sides by g-1.

\frac{x(g-1)}{g-1} =\frac{-c}{g-1\\}

x=\frac{c}{1-g}

Hope this helps!

5 0
2 years ago
Read 2 more answers
Wanahton is cooking a breadstick on a rectangular baking sheet measuring 9\dfrac129
salantis [7]

<u><em>Answer:</em></u>

The longest bread stick is approximately 16 in

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

The diagram representing the tray is shown in the attached image

From the diagram, we can note that the diagonal of the tray represents the hypotenuse of a right-angled triangle having legs 9.5 in and 13 in

<u>Therefore, to get the length of the hypotenuse, we can use the Pythagorean equation which is as follows:</u>

c² = a² + b²

where c is the length of the hypotenuse and a and b are the length of the two legs

<u>Substitute with the givens in the above equation to get the length of the hypotenuse as follows:</u>

c² = (9.5)² + (13)² = 259.25

c = 16.1 in which is approximately 16 in

<u>From the above, we can conclude that:</u>

The longest bread stick that can be fit straight along the diagonal of the tray is approximately 16 in

Hope this helps :)

7 0
2 years ago
Drew burned 1,800 calories Friday playing 1 hour of basketball and canoeing for 2 hours. On Saturday, he spent 2 hours playing b
V125BC [204]

Answer:

He burnt 1000 calories per hour when playing basketball.

Step-by-step explanation:

Let B be calories burned playing basketball, and C calories burned canoing.

1800 = B + 2C

3200 = 2B + 3C

From 1st equatipn, we get that B = 1800 - 2C

Replacing into the 2nd equation, we have:

3200 = 2(1800-2C) + 3C

3200 = 3600 - 4C + 3C

3200 = 3600 - 1C

C = 3600 - 3200

C = 400

Knowing C, we find B.

B = 1800 - 2C = 1800 - 2*400 = 1800 - 800 = 1000 calories.

6 0
2 years ago
Read 2 more answers
a computer shop charges 20 pesos per hour (or a fraction of an hour) for the first two hours and additional 10 pesos per hour fo
Serhud [2]

Answer:

The equation for the price, as a function of time in hours is:

P(x) = 20*x    for 0 ≤ x ≤ 2

P(x) = 40 + 10*(x - 2)  for  2 ≤ x

Now, we want to evaluate this function in 40 mins.

we know that 1 hour = 60mins.

Then 40 mins = (40/60) hours = 0.67 hours.

Then we input this in our function, and because this is smaller than 2, we use the first piece of our function:

P(0.67) = 20*0.67 = 13.4

So in 40 mins, the charge will be 13.4 pesos.

7 0
2 years ago
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