If a light bulb manufacturing company wants to​ estimate, with 90​% ​confidence, the mean life of compact fluorescent light bulbs to within ±150 hours and also assumes that the population standard deviation is 900 ​hours, how many compact fluorescent light bulbs need to be​ selected?       Question content area bottom Part 1 n=

IQs are normally distributed with a mean of 100 and a standard deviation of 15. Determine the percentage of IQ scores between 85 and 100, to the nearest whole number.

The mean life span of an African savanna elephant in the wild used to be 60 years. A recent sample of 15 deceased elephants in the wild yielded a mean life span of 62 years. Assume a normally distributed population with = 6 years. Test if the population mean life span of African savanna elephants has increased, using a = 0.05. Select one: O a. p-value = 0.0984, do not reject Ho. O b. p-value = 0.0984, reject Ho. c. p-value = 0.1968, do not reject Ho. d. p-value = 0.4522, do not Reject Ho.

The lifetime of a particular component is normally distributed with a mean of 1000 hours and a standard deviation of 100 hours. What is the 80th percentile of component lifetimes?

Assuming a population mean of 900 and a population standard deviation of 200 for LCSW scores. What percentage of individuals have LCSW scores greater than 1100? Plot answer on a normal distribution curve.

Assume that a certain data is approximately bell-shaped with mean 91 and standard deviation 6. Use the Empirical Rule to find the percent of the data between 85 and 103. Show all the necessary calculations.

Resting pulse rates for healthy adults are found to have approximately a Normal distribution with a mean of 69 beats per minute and a standard deviation of 8.5 beats per minute. Between what two values do the central 80% of all resting pulse rates lie?  what is lower value and  upper value ?

SAT math exam scores are normally distributed with mean 523 and standard deviation 89. If 2 million students took the SAT last year, about how many of them scored less than a 400?

Mean length of pregnancy is 268 days with a standard deviation of 15 days. Would a pregnancy that lasts for 235 days be significantly short in duration? Explain in 1 - 2 complete sentences. Edit View Insert Format Tools Table 12pt v Paragraph BIU A 2

Calculate the estimated standard error for the case where the sample standard deviation is 25 and the sample size 137. Answer to three decimal places if necessary, you may round up or down.