Let X distributed as a Normal random variable with a mean of 19 and a standard deviation of  4. A) What is the probability associated with an outcome between (15, 23)?

Kevin uses his mobile phone for X minutes each day. X is a random variable which may be modelled by a normal distribution. Given that 80% if X lie on a symmetrical interval of 17.7476 minutes and 38.2524 minutes. i) Determine the mean and standard deviation. ii) Hence, find the probability that on a particular day, Kevin uses his mobile phone between 10 and 20 minutes. iii) Find the probability that on 7 randomly selected days the mean time Kevin spends on his mobile phone is at least 30 minutes. iv) Hence, find the interval of X that on 7 randomly selected days Kevin spends on his mobile phone when the probability is 0.8.

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pleaseee sir solve question 24

The GPAs of all students enrolled at a large university have an approximately normal distribution with a mean of 3.02 and a standard deviation 0f 0.29. Find the probability that the mean GPA of a random sample of 20 students selected from this university is a) 3.10 or higher. b) 2.90 or lower. c) 2.95 to 3.11.

The length of human pregnancies from conception to birth is approximately Normal with mean 266 days and standard deviation of 16 days.  The probability that the average pregnancy length  for six randomly chosen women exceeds 270 days is about:

Assume that the amount of weight that male college students gain during their freshman year are normally distributed with a. Mean of u= 1.2 kg and a standard deviation of o= 5.1 kg  A. If 1 male college student is randomly selected, Find the probability that he gains between 0 and 3 kg during freshman year B. If 25 male college students are randomly selected find the probability that their mean weight gain during freshman year is between 0 and 3 kg  why can the normal distribution be used on pet b even though the sample size does not exceed 30?

Let x denote the time taken to run a road race. Suppose x is approx. normally distributed with a mean of 180 minutes and standard deviation of 20 minutes. If one runner is selected at random, what is the probability that this runner will complete this road race a) in less than 156 minutes? b) in 208 to 229 minutes

In regression analysis if a point has leverage then it must also be influential  a true  b false

Interpupillary distance (IPD) is the distance between the centers of the pupils of a person's left and right eyes. In adult males, IPD is approximately Normally distributed with a mean of 62.5 mm and a standard deviation of 6mm. Suppose you randomly select 5 adult males. What is the probability that their mean IPD is greater than 60mm? 1) 0.8243 2) 0.4995 3) 0.6615 4) 0.1757 5) 0.3885