She's practiced 2 1/3 hours already. Therefore, she has 1 2/3 hours left to practice. Let x be the minimum number of hours she needs to practice on each of the remaining two days.

Splitting up the remaining hours into two days, we get (5/3) divided by 2, which is 5/6 hours per day.

x is greater than or equal to 5/6 hours per day.

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New heat lamps are reported to have the mean lifespan of 100 hours with a standard deviation of 15 hours. Before replacing their

Tom [10]

Answer:

The correct option is C

The correct option is A

The correct option is B

Step-by-step explanation:

From the question we are told that

The population mean is $\mu = 100$

The standard deviation is $\sigma = 15$

The sample size is $n = 36$

The sample mean is $\= x = 105.1$

Generally

The null hypothesis is $H_o: \mu = 100 \ hours$

The alternative hypothesis is $H_a : \mu \ne 100\ hours$

Given that the null hypothesis is true then the distribution of sample means $\mu_{\= x }$ , from a sample size of 36 is mathematically represented as

$\mu_{\= x } = \mu$

=> $\mu_{\= x } = 100$

According to the Central Limit Theorem the test stated in the question is approximately normally distributed if the sample size is sufficiently large $(n > 30 )$ so given that the sample size is large n = 36