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tia_tia [17]
3 years ago
13

A study of the effects of acid rain on trees in the Hopkins Forest shows that 25 of 100 trees sampled exhibited some sort of dam

age from acid rain. This rate seemed to be higher than the 15% quoted in a recentEnvironmetricsarticle on the average proportion of damaged trees in the Northeast. Does the sample suggest that trees in the Hopkins Forest are more susceptible than trees from the rest of the region
Mathematics
1 answer:
Grace [21]3 years ago
5 0

Answer:

Yes

Step-by-step explanation:

We can test this claim using the one proportion z test :

x = 25 ; n = 100

Phat = x / n = 25 / 100 = 0.25

H0 : P = 0.15

H0 : P > 0.15

The test statistic :

Z = (phat - p) ÷ √p(1-p)/n

Z = (0.25-0.15) ÷ √(0.15*0.85)/100

Z = 2.8

Using the Pvalue from Zscore calculator :

α = 0.05

Pvalue (Z < 2.8) =0.0026

Pvalue < α ; We reject the Null

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Suppose the mean income of firms in the industry for a year is 95 million dollars with a standard deviation of 5 million dollars
GuDViN [60]

Answer:

Probability that a randomly selected firm will earn less than 100 million dollars is 0.8413.

Step-by-step explanation:

We are given that the mean income of firms in the industry for a year is 95 million dollars with a standard deviation of 5 million dollars. Also, incomes for the industry are distributed normally.

<em>Let X = incomes for the industry</em>

So, X ~ N(\mu=95,\sigma^{2}=5^{2})

Now, the z score probability distribution is given by;

         Z = \frac{X-\mu}{\sigma} ~ N(0,1)

where, \mu = mean income of firms in the industry = 95 million dollars

            \sigma = standard deviation = 5 million dollars

So, probability that a randomly selected firm will earn less than 100 million dollars is given by = P(X < 100 million dollars)

    P(X < 100) = P( \frac{X-\mu}{\sigma} < \frac{100-95}{5} ) = P(Z < 1) = 0.8413   {using z table]

                                                     

Therefore, probability that a randomly selected firm will earn less than 100 million dollars is 0.8413.

5 0
3 years ago
Solve the following triangle. Given A=51 degrees b=40 c=45
STALIN [3.7K]

Answer:

a=36.87\ units

B=57.47^o

C=71.53^o

Step-by-step explanation:

step 1

Find the length side a

Applying the law of cosines

a^2=b^2+c^2-2(b)(c)cos(A)

substitute the given values

a^2=40^2+45^2-2(40)(45)cos(51^o)

a^2=1,359.4466

a=36.87\ units

step 2

Find the measure of angle B

Applying the law of sines

\frac{a}{sin(A)} =\frac{b}{sin(B)}

substitute the given values

\frac{36.87}{sin(51^o)} =\frac{40}{sin(B)}

sin(B)=\frac{sin(51^o)}{36.87}{40}

B=sin^{-1}(\frac{sin(51^o)}{36.87}{40})=57.47^o

step 3

Find the measure of angle C

Remember that the sum of the interior angles in any triangle must be equal to 180 degrees

so

A+B+C=180^o

substitute the given values

51^o+57.47^o+C=180^o

108.47^o+C=180^o

C=180^o-108.47^o=71.53^o

5 0
4 years ago
Which expression is equivalent to 12x12x12x12x12x12x12x12x12x12x12
Alika [10]

Answer:

743008370688? or the 12¹¹

Step-by-step explanation:

8 0
3 years ago
Read 2 more answers
HELP ME PLZZZ
Setler79 [48]
H = height of triangle
b = length of triangle base
A = area of triangle

Recall the formula for area of a triangle :

A = 1/2 bh

Plug in what was given in the problem :

h = b - 5
A = 42

A = 1/2 bh
42 = 1/2 b (b-5) 

6 0
3 years ago
Read 2 more answers
Graph: y =
Snezhnost [94]

Answer:

Here it is. I recommend using desmos graphing calculator online! :)

7 0
3 years ago
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