# Thread: Need Help With Stats (2)!

1. ## Need Help With Stats (2)!

Hi everybody,

i would first like to apologise, in case i am posting this under the wrong section, as i am a new member. I am in need of help of some stats questions, please help me by providing answers and if possible, some explanation to it.

Thank you all!

6. A surprise quiz contains 4 multiple-choice questions: Question 1 has 5 suggested answers, Question 2 has 4, question 3 has 3 and Question 3 has two. A completely unprepared student decides to choose the answers at random. Let X denote the number of questions the student answers correctly. Determine the probability distribution of X.

7. The automatic opening device of a military cargo parachute has been designed to
open when the parachute is 200 m above the ground. Suppose opening altitude
actually has a normal distribution with mean value 200 m and standard deviation
40 m. Equipment damage will occur if the parachute opens at an altitude 100 m.
What is the probability that there is equipment damage to the payload of at least
one of five independent dropped parachutes?

2. Originally Posted by xsyenex
Hi everybody,

i would first like to apologise, in case i am posting this under the wrong section, as i am a new member. I am in need of help of some stats questions, please help me by providing answers and if possible, some explanation to it.

Thank you all!

6. A surprise quiz contains 4 multiple-choice questions: Question 1 has 5 suggested answers, Question 2 has 4, question 3 has 3 and Question 3 has two. A completely unprepared student decides to choose the answers at random. Let X denote the number of questions the student answers correctly. Determine the probability distribution of X.
What have you tried, we can't help if we can't tell what difficulties you are having

CB

3. Originally Posted by xsyenex
7. The automatic opening device of a military cargo parachute has been designed to
open when the parachute is 200 m above the ground. Suppose opening altitude
actually has a normal distribution with mean value 200 m and standard deviation
40 m. Equipment damage will occur if the parachute opens at an altitude 100 m.
What is the probability that there is equipment damage to the payload of at least
one of five independent dropped parachutes?
First find the probability p of equipment damage on a single drop (using the normal distribution given)

The second part is a binomial distribution problem, the number of payloads damaged has a binomial distribution B(p,5), and the probability that at least one payload is damaged is 1 - probability than none are damaged.

CB

4. hi, the problem i am looking at is, the question says "Equipment damage will occur if the parachute opens at an altitude 100 m."
i am not taught to use the function normalpdf in my graphic calculator, only normalcdf, which is cumulative.

hence i am thinking if the question is trying to say if equipment damage will occur at 100m, or below 100m and below?

5. captainblack,

for question 6, i dont even know what the question is asking me to do...what does it mean when it says "Determine the probability distribution of X."? what form is my answer going to take? what does the question want me to show?