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3 years ago

Can someone help me plz

Mathematics

1 answer:

galben [10]3 years ago

6 0

Step-by-step explanation:

the answer is in the image above

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3 years ago

Determine the exact and approximate circumference of the circle.

madam [21]

Answer:

C (circumference) =2×π×r

we've got a 30-60-90 triangle

which means 9=d√3, d=5.19 exact inches

or ≈5.20 inches

d=2r, r=5.20÷2≈2.60 inches

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3 0

3 years ago

Can someone help me with this please?

photoshop1234 [79]

Your answer is B ...

7 0

2 years ago

The top of the desk is shaped like a trapezoid the bases of the trapezoid are 26.5 and 30 cm long the area of the desk is 791 CM

kotegsom [21]

Answer:

28 cm

Step-by-step explanation:

Given that :

Area = 791 cm

Base, b1 = 26.5 cm

Base, b2 = 30 cm

Area, A of trapezoid :

A = 1/2 (a + b) h

Where a and b are the bases ;

791 = 1/2(26.5 + 30)h

791 = 0.5(56.5)h

791 = 28.25h

h = 791 / 28.25

h = 28 cm

5 0

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