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lyudmila [28]
3 years ago
5

A square has the sides length 2k-1 units. An equilateral triangle has the sides of the length k+2 units. the square and the tria

ngle have the same perimeter. what is the value of k?
I got k=3 I think I got wrong can someone please correct me???
Mathematics
1 answer:
AlladinOne [14]3 years ago
8 0
I think that you assumed that:
2k - 1 = k + 2

However we can't do this, because a square has 4 sides whilst a triangle only has 3 sides. 
This means that we can say
4(2k - 1) = 3(k + 2) 

We multiply by 4 due to 4 sides of the square, and by 3 due to the 4 sides of the triangle.

Lets expand the brackets, and solve it:

4(2k - 1) = 3(k + 2)
8k -4 = 3k + 6
5k -4 = 6    ( subtract both sides by 3x to collect the x values)
5k = 10      (add both sides by 4 to get the x's alone)
k = 2           (divide both sides by 5 to get what just x is)

So k = 2 units
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The ratio of boys to girls in a class is 3:5. There are 32 students in the class. How many more girls than boys are there?
Mandarinka [93]

Answer:

There are 8 more girls

Step-by-step explanation:

If you divide 32 by 8 (since the ratio is 3:5 which is 8 parts (3+5)). You get 4.

Thus, there are 12 boys and 20 because 3*4 is 12 and 5*4 is 20. 12+20 is 32.

6 0
3 years ago
Suppose we are testing people to see if the rate of use of seat belts has changed from a previous value of 88%. Suppose that in
Andreas93 [3]

Answer:

a) We would expect to see 500*0.88=440

b) z=\frac{0.9 -0.88}{\sqrt{\frac{0.88(1-0.88)}{500}}}=1.376  

p_v =2*P(Z>1.376)=0.167  

So the p value obtained was a very high value and using the significance level assumed \alpha=0.05 we have p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can said that at 5% of significance the true proportion is not significant different from 0.9.

The p value is a criterion to decide if we reject or not the null hypothesis, when p_v we reject the null hypothesis in other case we FAIL to reject the null hypothesis. And represent the "probability of obtaining the observed results of a test, assuming that the null hypothesis is correct".  

Step-by-step explanation:

Data given and notation

n=500 represent the random sample taken

X=450 represent the people that have the seat belt fastened

\hat p=\frac{450}{500}=0.9 estimated proportion of people that have the seat belt fastened

p_o=0.88 is the value that we want to test

\alpha represent the significance level

z would represent the statistic (variable of interest)

p_v{/tex} represent the p value (variable of interest)  Part aWe would expect to see 500*0.88=440Part bConcepts and formulas to use  We need to conduct a hypothesis in order to test the claim that the true proportion changes fro m 0.88.:  Null hypothesis:[tex]p=0.88  

Alternative hypothesis:p \neq 0.88  

When we conduct a proportion test we need to use the z statisitc, and the is given by:  

z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}} (1)  

The One-Sample Proportion Test is used to assess whether a population proportion \hat p is significantly different from a hypothesized value p_o.

Calculate the statistic  

Since we have all the info requires we can replace in formula (1) like this:  

z=\frac{0.9 -0.88}{\sqrt{\frac{0.88(1-0.88)}{500}}}=1.376  

Statistical decision  

It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.  

The significance level assumed is \alpha=0.05. The next step would be calculate the p value for this test.  

Since is a bilateral test the p value would be:  

p_v =2*P(Z>1.376)=0.167  

So the p value obtained was a very high value and using the significance level assumed \alpha=0.05 we have p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can said that at 5% of significance the true proportion is not significant different from 0.9.

The p value is a criterion to decide if we reject or not the null hypothesis, when p_v we reject the null hypothesis in other case we FAIL to reject the null hypothesis. And represent the "probability of obtaining the observed results of a test, assuming that the null hypothesis is correct".  

8 0
2 years ago
The diagonals of rectangle nopq intersect at point r. if qr=3x-4 and np=5x+20, solve for x.
FrozenT [24]
2(3x - 4) = 5x + 20
6x - 8 = 5x + 20
subtract 5x from both sides
x - 8 = 20
add 8 to both sides
x = 28


7 0
3 years ago
Read 2 more answers
A random sample of 36 students at a community college showed an average age of 25 years. Assume the ages of all students at the
Pavel [41]

Answer:

98% confidence interval for the average age of all students is [24.302 , 25.698]

Step-by-step explanation:

We are given that a random sample of 36 students at a community college showed an average age of 25 years.

Also, assuming that the ages of all students at the college are normally distributed with a standard deviation of 1.8 years.

So, the pivotal quantity for 98% confidence interval for the average age is given by;

             P.Q. = \frac{\bar X - \mu}{\frac{\sigma}{\sqrt{n} } } ~ N(0,1)

where, \bar X = sample average age = 25 years

            \sigma = population standard deviation = 1.8 years

            n = sample of students = 36

            \mu = population average age

So, 98% confidence interval for the average age, \mu is ;

P(-2.3263 < N(0,1) < 2.3263) = 0.98

P(-2.3263 < \frac{\bar X - \mu}{\frac{\sigma}{\sqrt{n} } } < 2.3263) = 0.98

P( -2.3263 \times {\frac{\sigma}{\sqrt{n} } < {\bar X - \mu} < 2.3263 \times {\frac{\sigma}{\sqrt{n} } ) = 0.98

P( \bar X - 2.3263 \times {\frac{\sigma}{\sqrt{n} } < \mu < \bar X +2.3263 \times {\frac{\sigma}{\sqrt{n} } ) = 0.98

98% confidence interval for \mu = [ \bar X - 2.3263 \times {\frac{\sigma}{\sqrt{n} } , \bar X +2.3263 \times {\frac{\sigma}{\sqrt{n} } ]

                                                  = [ 25 - 2.3263 \times {\frac{1.8}{\sqrt{36} } , 25 + 2.3263 \times {\frac{1.8}{\sqrt{36} } ]

                                                  = [24.302 , 25.698]

Therefore, 98% confidence interval for the average age of all students at this college is [24.302 , 25.698].

8 0
2 years ago
if each dimension of a unit cube is increased by 1. what is the ratio between the surface area of the new cube to that of the or
nexus9112 [7]

Answer:

4:1 or 4/1

Step-by-step explanation:

Original surface area: Each side is 1 * 1 = 1 and there are 6 sides, so 1 * 6 = 6.

New surface area: Each side is 2*2 = 4, and there are 6 sides, so 4 * 6 = 24

The ratio would be 24:6, or 4:1. As a fraction, this would be 4/1

4 0
3 years ago
Read 2 more answers
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