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forsale [732]
3 years ago
7

Find all solutions in the region [0,2pi) for the equation cos^2(2x)-sin^2(2x)=0

Mathematics
1 answer:
Lynna [10]3 years ago
4 0
\cos^{2}(2x)-\sin^{2}(2x)=0
\rightarrow \sin^{2}(2x)=\cos^{2}(2x)
\rightarrow \frac{\sin^{2}(2x)}{\cos^{2}(2x)}=1
\rightarrow \tan^{2}(2x)=1
\rightarrow \tan(2x)=\pm 1

2x can range anywhere in [0, 4\pi)
So:
\rightarrow 2x=\frac{\pi}{4}, \frac{3\pi}{4}, \frac{5\pi}{4}, \frac{7\pi}{4}, \frac{9\pi}{4}, \frac{11\pi}{4}, \frac{13\pi}{4}, \frac{15\pi}{4}
\rightarrow x=\frac{\pi}{8}, \frac{3\pi}{8}, \frac{5\pi}{8}, \frac{7\pi}{8}, \frac{9\pi}{8}, \frac{11\pi}{8}, \frac{13\pi}{8}, \frac{15\pi}{8}
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trapecia [35]
To answer this question here is what you would do. I can't give you the exact answer because there is not a line plot attached.

Count the number of X's above the number 5 1/2 feet. Put this number over the total number of X's you count (including the 5 1/2s).

This is your answer when you write these 2 pieces of information in fraction form.
5 0
3 years ago
John has two jobs. For daytime work at a jewelry store he is paid
djyliett [7]

Given Information:

John's mean monthly commission = μ = $10,000

Standard deviation of monthly commission = σ =  $2,000

Answer:

P(9,000 < X < 11,000) = 0.383\\\\P(9,000 < X < 11,000) = 38.3 \%

The probability that John's commission from the jewelry store is  between $9,000 and $11,000 is 38.3%

Step-by-step explanation:

What is Normal Distribution?

We are given a Normal Distribution, which is a continuous probability distribution and is symmetrical around the mean. The shape of this distribution is like a bell curve and most of the data is clustered around the mean. The area under this bell shaped curve represents the probability.  

We want to find out the probability that John's commission from the jewelry store is  between $9,000 and $11,000?

P(9,000 < X < 11,000) = P( \frac{x - \mu}{\sigma} < Z < \frac{x - \mu}{\sigma} )\\\\P(9,000 < X < 11,000) = P( \frac{9,000 - 10,000}{2,000} < Z < \frac{11,000 - 10,000}{2,000} )\\\\P(9,000 < X < 11,000) = P( \frac{-1,000}{2,000} < Z < \frac{1,000}{2,000} )\\\\P(9,000 < X < 11,000) = P( -0.5 < Z < 0.5 )\\\\P(9,000 < X < 11,000) = P( Z < 0.5 ) - P( Z < -0.5 ) \\\\

The z-score corresponding to 0.50 is 0.6915

The z-score corresponding to -0.50 is 0.3085

P(9,000 < X < 11,000) = 0.6915 - 0.3085 \\\\P(9,000 < X < 11,000) = 0.383\\\\P(9,000 < X < 11,000) = 38.3 \%

Therefore, the probability that John's commission from the jewelry store is  between $9,000 and $11,000 is 38.3%

How to use z-table?

Step 1:

In the z-table, find the two-digit number on the left side corresponding to your z-score. (e.g 1.4, 2.2, 0.5 etc.)

Step 2:

Then look up at the top of z-table to find the remaining decimal point in the range of 0.00 to 0.09. (e.g. if you are looking for 0.50 then go for 0.00 column)

Step 3:

Finally, find the corresponding probability from the z-table at the intersection of step 1 and step 2.

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What is the standard deviation of the following data set rounded to the nearest tenth? 56 ,78 ,123 , 34, 67, 91, 20
quester [9]

Answer:

The standard deviation of the following data set is 32.2

Step-by-step explanation:

step 1

Find the mean

we have

[56,78,123,34,67,9,20]

Sum the data and divided by the number of elements

[56+78+123+34+67+91+20]/7=469/7=67

step 2

For each number: subtract the Mean and square the result

[(56-67)^{2},(78-67)^{2},(123-67)^{2},(34-67)^{2},(67-67)^{2},(91-67)^{2},(20-67)^{2}]

[121,121,3,136,1,089,0,576,2,209]

step 3

Work out the mean of those squared differences

[121+121+3,136+1,089+0+576+2,209]/7=1,036

This value is called the "Variance"    

step 4

Take the square root of the variance

standard\ deviation=\sqrt{1,036}=32.2

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Answer:

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Step-by-step explanation:

Circumference is Pi x diameter

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