Introduction to Statistical Methods for the Life and Health Sciences
Instructor: Ivo Dinov, Asst. Prof.
Departments of Statistics & Neurology
Friday, Jan. 31, 2003
Please, submit your homeworks after class on the due date. See the
HW submission rules.
On the front page include the following
(HW_3_1) A manufacturer of disk drives for a well-known brand of computers expects 4% of the drives to malfunction during the computer’s warranty period. Let X be the number of disk drives, in a batch of 10 randomly selected disk drives, which malfunction during this period. X has a Binomial distribution.
- Identify n and p, the parameters of the Binomial random variable.
- In the context of this exercise, state the assumptions required for X to have a Binomial distribution.
- Are the Binomial assumptions satisfied here?
- Calculate the probability that:
- No disk drive will malfunction during the warranty period.
- Exactly one disk drive will malfunction during the warranty period.
- At least two disk drives will malfunction during the warranty period.
- Between 3 and 6 (inclusive) disk drives will malfunction during the warranty period.
(HW_3_2) Assume the distribution of human blood types in one geographic
region is: 30% type A; 11% type B; 49% type O and; 10% type AB. Suppose we
select one married couple at random, with the husband and the wife following
this blood type distribution.
- If the wife has type B blood, what is the probability that the husband has blood type B?
- What is the probability that both husband and wife have type A blood?
- What is the probability that at least one of them has blood type AB?
- What is the probability that they have the same blood type?
Last modified on
Ivo D. Dinov, Ph.D., Departments of Statistics and Neurology,
UCLA School of Medicine