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Jobisdone [24]
3 years ago
9

Can you help me on this?

Mathematics
1 answer:
Illusion [34]3 years ago
5 0

Answer:

y = 30

Step-by-step explanation:

We can use ratio's to solve this

40        20

-----  = -----------

100       20 + y


Using cross products

40 * (20+y) = 20*100

Distribute

800 + 40y = 2000

Subtract 800 from each side

40y = 2000-800

40y = 1200

Divide by 40

y = 1200/40

y =30

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According to an​ almanac, 60​% of adult smokers started smoking before turning 18 years old. ​(a) compute the mean and standard
larisa [96]
The given problem describes a binomial distribution with p = 60% = 0.6. Given that there are 400 trials, i.e. n = 400.

a.) The mean is given by:

\mu=np=400\times0.6=240

The standard deviation is given by:

\sigma=\sqrt{npq} \\  \\ =\sqrt{np(1-p)} \\  \\ =\sqrt{400(0.6)(0.4)} \\  \\ =\sqrt{96}=9.80


b.)  The mean means that in an experiment of 400 adult smokers, we expect on the average to get about 240 smokers who started smoking before turning 18 years.


c.) It would be unusual to observe <span>340 smokers who started smoking before turning 18 years old in a random sample of 400 adult​ smokers because 340 is far greater than the mean of the distribution.
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5 0
3 years ago
The test scores of a geometry class are given below. 90, 75, 72, 88, 85 The teacher wants to find the variance for the class pop
ella [17]
The data given as a whole would be called ungrouped data. Now to get the variance, you will need the formula:

s^2=   <u>Σ(x-mean)^2</u>
                   n      

x = raw data
mean = average of all data
n = no. of observations
s^2 = variance

Now we do not have the mean yet, so you have to solve for it. All you need to do is add up all the data and divide it by the number of observations. 

Data: <span>90, 75, 72, 88, 85        n= 5  
</span>Mean=<u>Σx</u>
            n
Mean = <u>90+75+72+88+85 </u>  = <u>410</u> = 82
                        5                        5

The mean is 82. Now we can make a table using this.

The firs column will be your raw data or x, the second column will be your mean and the third will be the difference between the raw data and the mean and the fourth column will be the difference raised to two. 

90-82 = 8
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75-82 = -7
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72-82 = -10
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88-82=6
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85-82=3
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Now you have your results, you can now tabulate the data:

 x      mean         x-mean        (x-mean)^2     
90       82                8                      64                       
75       82               -7                      49
72       82              -10                    100
88       82                6                       36
85       82                3                       9

Now that you have a table, you will need the sum of (x-mean)^2 because the sigma sign Σ in statistics, means "the sum of."

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This will be the answer to your question. The value of the numerator of the calculation will be 258.

 
<u>
</u>
6 0
4 years ago
A textbook store sold a combined total of 426 math and sociology textbooks in a week. The number of math textbooks sold was 88 m
SOVA2 [1]
Let m and s be the number of math and sociology books sold respectively.

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s+88+s=426 combine like terms on left side

2s+88=426  subtract 88 from both sides

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s=169, since m=s+88

m=169+88=257

So 257 math and 169 sociology textbooks were sold.
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