Question

A student selects his answers on a true/false examination by tossing a coin (so that any particular answer has a .50 probability of being correct). He must answer at least 70% correctly in order to pass. Find his probability of passing when the number of questions is

Answer 1

If the exam has 10 questions, the probability will be 0,0078

Explanation:

To get the probability equally likely of having the question right we use the following formula

P=# of possibilities that meet the condition / #of equally likely possibilities.

Each question has the following probability of being right.

P=1/2

In this case, we considered 10 questions as the total exam. So, we have to get 7 questions right to pass the exam (70%).

To get the probability of several independent events occurring together, we just multiply the probability of the all the events.

P(passing the exam)=1/2*1/2*1/2*1/2*1/2*1/2*1/2=0,0078