I just need help with b and f

Standard deviation can only be used for variables measured at the interval level central level nominal level ordinal level

The top part please

The distribution of scores of students heading to college in the math section of the SAT follows a normal distribution with mean u = 520 and standard deviationo = 115. X = The score of a student heading to college in the math section of the SAT X = The mean score of 100 students heading to college in the math section of the SAT EX = The total score of 100 students heading to college in the math section of the SAT (Please show all formulas, calculations and the curves) (a) What math SAT score is 2 standard deviations below the mean? (b) What is the probability that the score of a student is less than 480? (c) What is the distribution of X? (d) What is the probability that the mean scores of 100 students is between 518 and 530? (e) What is the distribution of EX? (1) What is the probability that the total scores of 100 students is more than 51500? (g) What is the 65th percentile for the mean scores of 100 students?

A distribution of values is normal with a mean of 60 and a standard deviation of 3. Find the interval containing the mid-68% of the values. Please show your answer to 1 decimal place. Interval = (,)

How to find the standard deviation

Assume that the weights of individuals are independent and normally distributed with a mean of 160 pounds and a standard deviation of 30 pounds. Suppose that 20 people squeeze into an elevator that is designed to hold 3400 pounds. 5. (6) (a) What is the standard deviation of the total weight of 20 people?

Suppose the distribution of maximum monthly January temperatures in Sydney is normal with mean, μ = 25.95 OC and a standard deviation, σ = 1.13 OC. What is the value of the temperature that cuts off the lower 2.5% of this population?  (1 dp)   What is the value of the temperature that cuts off the upper 25% of this population?   (1 dp)

Lecture(10.1): The mean of the population is 50. The standard deviation is 10. (a) What is the probablity that a randomly  selected person from a population has a mean score between 50 and 75 ? (b) if a person Z score is 1.38. what is his raw score? (c) if a person has raw score of -.91. What is his raw score?.

If the professor grades on a curve​ (for example, the professor could give​ A's to the top​ 10% of the​ class, regardless of the​ score), is a student better off with a grade of 90 on the exam with a mean of 72and a standard deviation of 9 or a grade of 73 on a different​ exam, where the mean is 69 and the standard deviation is 4​?Show your answer statistically and explain.   A student is ▼   better off OR worse off with a grade of 90 on the exam with a mean of 72 and a standard deviation of 9 because the Z value for the grade of 90 is ? and the Z value for the grade of 73 on the different exam is ?   ​(Round to two decimal places as​ needed.)