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3 years ago

Two rays that form a straight line and that intersect a point?

Mathematics

1 answer:

yan [13]3 years ago

4 0

The question doesn't seem to be a complete one ..

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9 students volunteer for a committee. How many different 7-person committees can be chosen? 1 181,440 362,880 36

Mama L [17]

Its 36. use the type A!/B!(A-B)!

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3 years ago

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If the squareof a positive number is increased by 3 times the number the result is 54 find the number

denpristay [2]

Positive square 162. <span />

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3 years ago

The service life of a battery used in a cardiac pacemaker is assumed to be normally distributed. A random sample of ten batterie

Fittoniya [83]

Answer:

The confidence interval is $25.16 < \mu < 26.85$

Step-by-step explanation:

From the question we are given a data set

25.5, 26.1, 26.8, 23.2, 24.2, 28.4, 25.0, 27.8, 27.3, and 25.7.

The mean of the this sample data is

$\= x = \frac{\sum x_i}{n}$

where is the sample size with values n = 10

$\= x = \frac{25.5+ 26.1+ 26.8+23.2+ 24.2+ 28.4+ 25.0+ 27.8+ 27.3+ 25.7}{10}$

$\= x = 26$

The standard deviation is evaluated as

$\sigma = \sqrt{\frac{\sum (x-\= x)}{n} }$

substituting values

$= \sqrt{\frac{ ( 25.5-26)^2, (26.1-26)^2, (26.8-26)^2, (23.2-26)^2}{10} }$

$\cdot \ \cdot \ \cdot \sqrt{\frac{ ( 24.2-26)^2, (28.4-26)^2+( 25.0-26)^2+ (27.8-26)^2+( 27.3-26)^2+( 25.7-26)^2}{10} }$

$\sigma = 1.625$

The confidence level is given as 90% hence the level of significance is calculated as

$\alpha = 100 -90$

$\alpha =10$ %

$\alpha = 0.10$

Now the critical values of $\frac{\alpha }{2}$ is obtained from the normal distribution table as

$Z_{\frac{\alpha }{2} } = 1.645$

The reason we are obtaining the critical values of $\frac{\alpha }{2}$ instead of $\alpha$ is because we are considering two tails of the area under the normal curve

The margin of error is evaluated as

$MOE = Z_{\frac{\alpha }{2} } * \frac{\sigma }{\sqrt{n} }$

substituting values

$MOE = 1.645 * \frac{1.625 }{\sqrt{10} }$

$MOE = 0.845$

The 90%, two sided confidence interval is mathematically evaluated as

$\= x - MOE < \mu < \= x + MOE$

$26 - 0.845 < \mu < 26 + 0.845$

$25.16 < \mu < 26.85$

Given that the lower and the upper limit is greater than 25 then we can assure the manufactures that the battery life exceeds 25 hours

5 0

3 years ago

I need help fast ooooooo

Stels [109]

Answer: A

Step-by-step explanation:

Because 2x3=5

4 0

3 years ago

How many ml of 1:4 solution and how many ml of sterile water are needed to prepare 600 ml of 1:20 solution ?

Delvig [45]

Answer:

Approximately 143 mL of 1:4 solution and 457 mL of water

Step-by-step explanation:

A 1:4 solution has a concentration of 1/(1+4) = 1/5 or 20%.

Similarly, a 1:20 solution has a concentration of 1/(1+20) = 1/21 or 4.76%.

If x is the mL of 20% solution and y is the mL of water, then:

x + y = 600

1/5 x = 1/21 (600)

Solve:

x = 5/21 (600)

x ≈ 143

y ≈ 457

You need approximately 143 mL of 1:4 solution and 457 mL of water.

4 0

3 years ago