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3 years ago

EASY QUESTION. HELP NEED PLZ.

Mathematics

1 answer:

Setler79 [48]3 years ago

3 0

Answer:

1: 30 degrees

Step-by-step explanation:

In Physics, we have the law of reflection. This law states that when light rays hit the smooth surface of mirror or any smooth polished surface, the angle of incidence is equivalent to the angle of reflection.

Mathematically:

Angle of incidence = Angle of reflection

From the above question, the angle of incidence is on a smooth plane mirror = 30°

Since:

Angle of incidence = Angle of reflection

30° = 30°

Therefore, based on the law of reflection, the Angle of reflection = 30°

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Solve the equation. Check the solution.<br> 1/2(2x-1)= -1/9 -7/9

Thepotemich [5.8K]

Answer:

hope this can help you (^^)

3 0

3 years ago

How do i calculate? All the way to s_75. It’s so long

mina [271]

Answer:

-675

Step-by-step explanation:

The sum can be broken into parts that you know. Here, one of those parts is the sum of numbers 1 to n. That sum is given by n(n+1)/2.

$\displaystyle S_{75}=\sum\limits_{n=1}^{75}{(67-2n)}=\sum\limits_{n=1}^{75}{67}-2\sum\limits_{n=1}^{75}{n}\\\\=75\cdot 67-2\dfrac{75(75+1)}{2}=75(67-76)\\\\=\bf{-675}$

Another way to do this is to realize the sequence of numbers is an arithmetic sequence with a first term of 65 and a last term of 67-2·75 = -83.

The sum of an arithmetic sequence is found by multiplying the number of terms by their average value. Their average value is the average of the first and last terms.

The average value of those 75 terms is (65 +(-83))/2 = -9, so their sum is ...

75(-9) = -675

7 0

3 years ago

Could someone explain.This brainliest.

LekaFEV [45]

$Mikayla-132\\\\Zack:\\one\ fourth\ as\ much\ candy\ as\ Mikayla\\\\\dfrac{1}{4}\cdot132=\dfrac{132}{4}=33\\\\Kim:\\three\ times\ as\ much\ candy\ as\ Zack\\\\3\cdot33=99\\\\Answer:\ 132+33+99=264\ pieces$

4 0

3 years ago

Do teachers find their work rewarding and satisfying? An article reports the results of a survey of 397 elementary school teache

Tju [1.3M]

Answer:

The 95% confidence interval would be given (0.0109;0.1651).

We are confident at 95% that the difference between the two proportions is between $0.0109 \leq p_{elementary} -p_{High school} \leq 0.1651$

Step-by-step explanation:

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".

$p_A$ represent the real population proportion for elementary school

$\hat p_A =\frac{226}{397}=0.569$ represent the estimated proportion for elementary school

$n_A=397$ is the sample size required for Brand A

$p_B$ represent the real population proportion for high school teachers

$\hat p_B =\frac{129}{268}=0.481$ represent the estimated proportion for high school teachers

$n_B=268$ is the sample size required for Brand B

$z$ represent the critical value for the margin of error

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{p(1-p)}{n}})$

The confidence interval for the difference of two proportions would be given by this formula

$(\hat p_A -\hat p_B) \pm z_{\alpha/2} \sqrt{\frac{\hat p_A(1-\hat p_A)}{n_A} +\frac{\hat p_B (1-\hat p_B)}{n_B}}$

For the 95% confidence interval the value of $\alpha=1-0.95=0.05$ and $\alpha/2=0.025$ , with that value we can find the quantile required for the interval in the normal standard distribution.

$z_{\alpha/2}=1.96$

And replacing into the confidence interval formula we got:

$(0.569-0.481) - 1.96 \sqrt{\frac{0.569(1-0.569)}{397} +\frac{0.481(1-0.481)}{268}}=0.0109$

$(0.569-0.481) + 1.96 \sqrt{\frac{0.569(1-0.569)}{397} +\frac{0.481(1-0.481)}{268}}=0.1651$

And the 95% confidence interval would be given (0.0109;0.1651).

We are confident at 95% that the difference between the two proportions is between $0.0109 \leq p_{elementary} -p_{High school} \leq 0.1651$

5 0

3 years ago

Georgie's toy car collection consists of modern and classic cars. He has four times as many classic cars as he cars. If he has 3

White raven [17]

Use a system of equations to solve this problem. Let "x" represent the number of classic cars, and "c" represent the number of cars.

320 = x + c
x = 4c

In this case, it'll be easiest to use the substitution method to solve the system of equations.

320 = (4c) + c
320 = 5c

Now solve for "c":

320/5 = c
c = 64

Since you now know there are 64 regular cars, you can subtract that from the total amount for the number of classic cars.

320 - 64 = 256

There are 256 classic cars.

To check the answer, multiply 64 by 4 and make sure it equals 256.

64 x 4 = 256

4 0

3 years ago