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Mnenie [13.5K]
3 years ago
8

1/2r+2(3/4r-1)=1/4r+6

Mathematics
1 answer:
bixtya [17]3 years ago
3 0
I think r should equal 32/7
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Lightbulbs of a certain type are advertised as having an average lifetime of 750 hours. The price of these bulbs is very favorab
Katyanochek1 [597]

Answer:

(a) Customer will not purchase the light bulbs at significance level of 0.05

(b) Customer will purchase the light bulbs at significance level of 0.01 .

Step-by-step explanation:

We are given that Light bulbs of a certain type are advertised as having an average lifetime of 750 hours. A random sample of 50 bulbs was selected,  and the following information obtained:

Average lifetime = 738.44 hours and a standard deviation of lifetimes = 38.2 hours.

Let Null hypothesis, H_0 : \mu = 750 {means that the true average lifetime is same as what is advertised}

Alternate Hypothesis, H_1 : \mu < 750 {means that the true average lifetime is smaller than what is advertised}

Now, the test statistics is given by;

       T.S. = \frac{Xbar-\mu}{\frac{s}{\sqrt{n} } } ~ t_n_-_1

where, X bar = sample mean = 738.44 hours

               s  = sample standard deviation = 38.2 hours

               n = sample size = 50

So, test statistics = \frac{738.44-750}{\frac{38.2}{\sqrt{50} } } ~ t_4_9

                            = -2.14

(a) Now, at 5% significance level, t table gives critical value of -1.6768 at 49 degree of freedom. Since our test statistics is less than the critical value of t, so which means our test statistics will lie in the rejection region and we have sufficient evidence to reject null hypothesis.

Therefore, we conclude that the true average lifetime is smaller than what is advertised and so consumer will not purchase the light bulbs.

(b) Now, at 1% significance level, t table gives critical value of -2.405 at 49 degree of freedom. Since our test statistics is higher than the critical value of t, so which means our test statistics will not lie in the rejection region and we have insufficient evidence to reject null hypothesis.

Therefore, we conclude that the true average lifetime is same as what it has been advertised and so consumer will purchase the light bulbs.

6 0
3 years ago
How can find the estimate of the sum of the two fractions​
vodka [1.7K]

Answer:

To make a high estimate for the sum of two fractions, find the commnon denominator and add them.

Step-by-step explanation:

To make a high estimate for the sum of two fractions in a word problem, rhe following steps are required.

Let the two fractions be represented as and

To perfrom the operation +

Step 1 : Check if the denominators of the fraction are same. If so then, then add the numerators directly by keeping the same denominator.

Step 2: If the denominators are different, then find the common denominator between the fractions and multiply them accordingly. Then perform the addition operation.

6 0
3 years ago
Please help brainliest to correct answer
jekas [21]
The first one is -4 and the second one is 6.
7 0
3 years ago
Read 2 more answers
help I’ll give brainliest
Tema [17]

Answer: The median of the upper half of a set of data is the upper quartile ( UQ ) or Q3 . The upper and lower quartiles can be used to find another measure of variation call the interquartile range . The interquartile range or IQR is the range of the middle half of a set of data.

Step-by-step explanation:

6 0
3 years ago
The seventh-grade class is building target areas for a PE activity. The bases for the game will be circular in shape. The diamet
Scilla [17]
To calculate the area it is pi*r^2

so since r = 1/2 d

2.5^2 * pi = area
or
19.625
8 0
3 years ago
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