Whenever an even number is added to an odd number, the result is odd. Whenever an even number is added to an even number, the result is even. 

Given that all the numbers in set  are even, there is a 100 percent chance of an even number being selected; however in set , one of the three numbers is odd, so there is a one third chance of an odd number being selected. 

Given that the sum of an even number and an odd number is odd, there is a probability of  that the sum of a number randomly selected from set  and from set  wil be an odd number. 

The only way in which a negative number would be acheived by subtracting  is if  was equal to 2, and any number was selected for . 

Therefore, the chance of  resulting in a negative number would be equal to the odds of selecting 2 from set . Given that there are four numbers in set , there is a one fourth chance. 

Thus, the correct answer is .

The only way that a product of  will be acheived is if the number  is selected from set , and the number  is selected from set . 

There is a one half chance of the number 4 being selected and a one half chance of the number 6 being selected, given that each set contains two numbers. 

Therefore, the probability of both these number being chosen is:

If Mark flips a coin, the chance that it will land on heads is . On a die, there are 2 out of 6 numbers that are a multiple of 3 (3 and 6); therefore, there is a  chance that the dice will be a multiple of 3. 

The probability that the coin will land on heads and that the dice will be a multiple of 3 is:

Given that there are six values that a die may show when rolled, there is a  chance that either dice will show a value of 1. Thus, the chance that both dice will show a value of 1 is equal to , which is equal to .

Thus,  is the correct answer. 

To find the probability of an event, you divide the possible outcomes of that event by total outcomes.  

The event outcomes would be the  seniors on the bus.  

The total outcomes is the number of students on the bus which is 

.  

So the probability of picking a senior would be 

.

There are  cards in a deck.  

There are four suits of cards including spades.  

They make up an even amount of the deck each.  

Since there are four of the suits, each represent  of the deck and that is the probability of drawing one.

To find the probability of an event, we use the following:

So, when looking at the event of drawing a 2 from a deck of cards, we get

It is 4 because we can draw a 2 from a deck of cards 4 different ways:

• 2 of hearts
• 2 of diamonds
• 2 of clubs
• 2 of spades

Now, 

because there are 52 cards in the entire deck.  Now,

We can simplify, we get

Therefore, the probability of drawing a 2 from a deck of cards is 

To find the probability of an event, we use the following:

So, when looking at the event of drawing a 9 of hearts from a deck of cards, we get

It is 1 because we can draw a 9 of hearts from a deck of cards in only 1 way:

• 9 of hearts

Now, 

because there are 52 cards in the entire deck.  Now,

Therefore, the probability of drawing a 2 from a deck of cards is 

Given that  of the class is girls, and there are  students, we must first determine how many girls are in the class. 

Because  is double the value of ,  is double the value of .  should be half of .

If  of the  girls wear skirts, then we can subtract to find the number of girls not wearing skirts.