SOLUTION: Assume that on a standardized test of 100 questions, a person has a probability of 80% of answering any particular question correctly. Find the probability of answering between 70

Question 923600: Assume that on a standardized test of 100 questions, a person has a probability of 80% of answering any particular question correctly. Find the probability of answering between 70 and 80 questions, inclusive, correctly.
P(70 ≤ X ≤ 80)=?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Assume that on a standardized test of 100 questions, a person has a probability of 80% of answering any particular question correctly. Find the probability of answering between 70 and 80 questions, inclusive, correctly.
P(70 ≤ X ≤ 80)=?
-----
mean = np = 100*0.8 = 80
std = sqrt(npq) = sqrt(80*0.20) = 4
-------------------------
z(70) = (70-80)/4 = -5/2
---
z(80) = 0
-----------------
P(7<= x <=80) = P(-5/2)<= z <= 0) = 0.49
---------------
Cheers,
Stan H.
===============
RELATED QUESTIONS
Assume that on a standardized test of 100 questions, a person has a probability of 85% of (answered by stanbon)

Of the 538 people who had an annual check-up at a doctor’s office, 215 had high blood... (answered by ikleyn)

Here is a simple probability model for multiple-choice tests. Suppose that a student has... (answered by stanbon)

Here is a simple probability model for multiple-choice tests. Suppose each student has... (answered by stanbon)

Scores for a particular standardized test are normally distributed with a mean of 80 and... (answered by Boreal,Edwin McCravy)

Scores for a particular standardized test are normally distributed with a mean of 80 and (answered by ewatrrr)

Find the probability of correctly answering the first 2 questions on a multiple choice... (answered by jorel1380)

FIND THE PROBABILITY OF CORRECTLY ANSWERING THE FIRST 4 QUESTIONS ON A MULTIPLE CHOICE... (answered by jorel1380)

5.Find the probability of correctly answering the first 4 questions on a multiple choice... (answered by fractalier)