Practical 1 2020 Sem 2.docx - Practical 1 1 As part of a study on plant growth a plant physiologist grew 13 individually potted soybean seedlings of the

# Practical 1 2020 Sem 2.docx - Practical 1 1 As part of a...

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Practical 1 1. As part of a study on plant growth, a plant physiologist grew 13 individuallypotted soybean seedlings of the type called “Wells II.” She raised the plantsin a greenhouse under identical environmental conditions (light, temperature,soil and so on). She measured the total stem length (in cm) for each plantafter 16 days of growth. The results are as follows:20.2 21.9 22.3 20.0 19.4 22.0 21.4 22.0 21.9 19.7 21.5 20.51.1A point estimate for the mean stem length of “Wells II” soybean seedlings onday 16 of growth (accurate to 4 decimal places) is: ______1.2 A point estimate for the standard deviation of the stem length of “Wells II”soybean seedlings on day 16 of growth (accurate to 4 decimal places) is:______2. At a trout farm in the Lowveld the mean weight of trout in a pond is to beestimated by means of a 99% confidence interval. A random sample of 36trout from this pond was caught and weighed, and they showed a meanweight of 560g with standard deviation of 84g. Construct the confidenceinterval.3. A standard flammability test for fabric is to place a standard-sized piece offabric under a flame for a fixed period of time, and then measure the length ofthe charred portion of fabric. Suppose the procedure is carried out using asample of 64 such portions of fabric and the average length of charredportions of fabric was 3 cm with a variance of 0.16 cm2. Construct a 90%confidence interval for the average length of charred portions of this fabric. 4.From a sample of 100 Bloemfontein car commuters, the sample mean time tocommute to work daily was found to be 35.8 minutes. It is known that thepopulation standard deviation is 20 minutes. 4.1Find the standard error.4.2 Find the margin of error with a 90% confidence level.4.3Find the margin of error with a 95% confidence level.4.4Find the margin of error with a 99% confidence level.4.5Find the 90% confidence interval for the actual mean time taken by all carcommuters in Bloemfontein to travel to work daily. 4.6Find the 95% confidence interval for the actual mean time taken by all carcommuters in Bloemfontein to travel to work daily. 20.5