Ask question

Ask question

All categories

2 years ago

14

At Southside Middle school, 30% if the students play an instrument. There are 310 students. How many students play an instrument

? Answer correctly for Brainly

1 answer:

Svetach [21]2 years ago

3 0

30% converted to a decimal is 0.30
310 x 0.3 = 93 students play an instrument

You might be interested in

Marco needs to buy some dog food. At the nearest store, 3 bags of dog food cost $6.75. how much would he spend spend on six ba

ipn [44]

Your answer would be $13.50 because is 3 bags cost 6.75 and you need 6 bags then just multiply the 6.75 by 2 and you get your answer :)

7 0

3 years ago

A random sample of size n1= 25, taken from a normal population with a standard deviation σ1= 5, has a mean X1= 80. A second rand

sesenic [268]

Answer:

The 94% confidence interval would be given by $2.898 \leq \mu_1 -\mu_2 \leq 7.102$

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X_1 =80$ represent the sample mean 1

$\bar X_2 =75$ represent the sample mean 2

n1=25 represent the sample 1 size

n2=36 represent the sample 2 size

$\sigma_1 =5$ sample standard deviation for sample 1

$\sigma_2 =3$ sample standard deviation for sample 2

$\mu_1 -\mu_2$ parameter of interest.

The confidence interval for the difference of means is given by the following formula:

$(\bar X_1 -\bar X_2) \pm z_{\alpha/2}\sqrt{\frac{\sigma^2_1}{n_1}+\frac{\sigma^2_2}{n_2}}$ (1)

The point of estimate for $\mu_1 -\mu_2$ is just given by:

$\bar X_1 -\bar X_2 =80-75=5$

Since the Confidence is 0.94 or 94%, the value of $\alpha=0.06$ and $\alpha/2 =0.03$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.03,0,1)".And we see that $z_{\alpha/2}=1.88$

The standard error is given by the following formula:

$SE=\sqrt{\frac{\sigma^2_1}{n_1}+\frac{\sigma^2_2}{n_2}}$

And replacing we have:

$SE=\sqrt{\frac{5^2}{25}+\frac{3^2}{36}}=1.118$

Confidence interval

Now we have everything in order to replace into formula (1):

$5-1.88\sqrt{\frac{5^2}{25}+\frac{3^2}{36}}=2.898$

$5+1.8\sqrt{\frac{6^2}{36}+\frac{7^}{49}}=7.102$

So on this case the 94% confidence interval would be given by $2.898 \leq \mu_1 -\mu_2 \leq 7.102$

7 0

2 years ago

If a 24-kg mass stretches a spring 15 cm, what mass will stretch the spring 10 cm

natulia [17]

Answer:

<h2>16kg</h2>

Step-by-step explanation:

This problem is borers on elasticity of materials.

according to Hooke's law,<em> "provided the elastic limit of an elastic material is not exceeded the the extension e is directly proportional to the applied force."</em>

$F= ke$

where F is the applied force in N

k is the spring constant N/m

e is the extension in meters

Given data

mass m= 24kg

extensnion=15cm in meters= $\frac{15}{100}$ = $0.15m$

we can solve for the spring constant k

we also know that the force F = mg

assuming $g=9.81m/s^{2}$

therefore

$24*9.81=k*0.15\\235.44=k*0.15\\k=\frac{235.44}{0.15} \\k=1569.6N/m\\$

We can use this value of k to solve for the mass that will cause an extension of $10cm= 0.1m$

$x*9.81=1569.6*0.1\\\\x= \frac{156.96}{9.81} \\\x= 16kg$

5 0

2 years ago

Sloan [31]

You take 94.5 and divide by 4.5 get 21

4 0

2 years ago

Read 2 more answers

One operator is holding a laser pointer at a height of 9 feet whose beam is reflected on a horizontal reflecting surface at a po

lutik1710 [3]

Answer:

The height (in feet) at which the laser will impact the wall is 6.75 feet

Step-by-step explanation:

The given parameters are;

The height from which the laser beam operator is holding the laser = 9 feet

The horizontal distance away from the pointer the beam is reflected = 8 feet

Given that we have;

$f(x) = \dfrac{9}{8} \times \left | x - 8\right | = y$

When x = 8, the point of reflection, the height, f(x) is given as follows;

$f(x) = \dfrac{9}{8} \times \left | 8 - 8\right | = 0$

When x = 7, the point of reflection, the height, f(x) is given as follows;

$f(x) = \dfrac{9}{8} \times \left | 7 - 8\right | = \dfrac{9}{8}$

Therefore, given that the point of reflection is at an elevation of 0 relative to the 9 feet of the laser source (pointer), by tan rule, we have;

$tan(\theta) = \dfrac{Opposite \ side}{Adjacent \ side} =\dfrac{9}{8} = \dfrac{h}{7}$

Where;

h = The height at which the laser meets the wall

$h = \dfrac{9 \times 7}{8} =7.875$

Given that the wall the laser meets is at the point x with elevation 9/8, the height, y, at which the laser meets the wall is therefore;

$y = \dfrac{9 \times 7}{8} - \dfrac{9}{8} = \dfrac{54}{8} = 6.75 \ feet$

The height (in feet) at which the laser will impact the wall = 6.75 feet.

7 0

3 years ago