SOLUTION: A biology gives a surprise quiz consisting of 15 multiple choice questions with 5 answer options. Assume an unprepeared student decides to randomly select answers. What is the ch
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Question 247205: A biology gives a surprise quiz consisting of 15 multiple choice questions with 5 answer options. Assume an unprepeared student decides to randomly select answers. What is the chance this student has
a. The first 7 answers correct and the last three answers wrong
b. Any 7 or more of the questions correct Answer by edjones(8007) (Show Source):
You can put this solution on YOUR website! a. (1/5)^7(4/5)^3=.00000655...
.
b. This is too long to write out the expansion.
Let x=.2 and y=.8
expand (x+y)^15
Eliminate bits when x has an exponent of less than 7
.0181... Answer.
.
Ed
