Answer:
12+8+7=27
Step-by-step explanation:
just normal addition
There are 8 possible outcomes for a marble being drawn and numbered.
{1,2,3,4,5,6,7,8}
There are 4 possible outcomes for a card being selected from a standard deck.
{ <span>hearts, diamonds, clubs, spades}
So the number of outcomes in the sample space would be 8 x 4 = 32.
In the event "an even number is drawn", there are only 4 possible outcomes for a marble being drawn, {2,4,6,8}, whereas there are still 4 possible outcomes for a suit. So the number of outcomes in the event is 4 x 4 = 16.
</span><span>In the event "a number more than 2 is drawn and a red card is drawn", there are 6 possible outcomes for the marble being drawn, {3,4,5,6,7,8}, whereas there are only two possible suits for a card being selected as red, {heart, diamond}. So the number of outcomes in this event is 6 x 2 = 12.
In the event </span><span>"a number less than 3 is drawn or a club is not drawn", the number drawn could be 1 or 2 whereas a spade/heart/diamond could be selected. So the number of outcomes is 2 x 3 = 6.</span><span>
</span>
Answer:
The probability that the student answers at least seventeen questions correctly is 
.
Step-by-step explanation:
Let the random variable <em>X</em> represent the number of correctly answered questions.
It is provided all the questions have five options with only one correct option.
Then the probability of selecting the correct option is,
There are <em>n</em> = 20 question in the exam.
It is also provided that a student taking the examination answers each of the questions with an independent random guess.
Then the random variable can be modeled by the Binomial distribution with parameters <em>n</em> = 20 and <em>p</em> = 0.20.
The probability mass function of <em>X</em> is:
Compute the probability that the student answers at least seventeen questions correctly as follows:
Thus, the probability that the student answers at least seventeen questions correctly is .
