In order to find the odds of two events happening, you multiply the odds of each event happening by the other. 

Here, the odds of one event happening is , and the odds of the other event happening are also .

We can solve by multiplying:

The chance of both accidents being caused by cell phone use is .

If Lisa flipped a quarter three times, the possibility of it being heads all three times is calculated by multiplying the chance of the quarter being heads on each occasion.

Each try has the same chance: .

Given that each time a quarter is flipped, there is a  chance of it being heads, the probability of it being heads all three times would be . 

When Edward flips the penny the first time, there is a 100% chance that the penny will be either heads or tails.

When Edward flips the penny the second time, there is a 50% chance that the second flip will be the same as the first: 50% chance that the second flip will be heads if the first flip was heads, and 50% chance the second flip will be tails if the first flip was tails.

The correct answer is , which is equal to 50%.

Let's start with the initial conditions: 4 yellow marbles and 6 blue marbles.

Yellow: X X X X

Blue X X X X X X

Total: 10 marbles

One yellow marble is picked out.

Yellow: X X X

Blue X X X X X X

Total: 9 marbles

The probability that the next marble will be blue is equal to:

The fraction can be reduced.

The chance that the next marble will be blue is .

There are two ways to solve this problem.

The first is to look at the probability of each coin. There is a one-in-three chance that the first coin will be A. If this happens, then there will be two coins left. This means that the chance that the second coin is B will be one-in two. If this happens, then there will be a 100% chance that the last coin will be C. Multiply each term together to find the total probability of the event.

The second way to solve is to look at the possible combinations of coins.

ABC

ACB

BAC

BCA

CAB

CBA

There are six possible orders, one of which is our target; therefore, there is a one-in-six chance that the predicted outcome will happen.

Since Emily baked a cake of 9 pieces and Rebecca ate 1 slice, 8 slices remain. The total odds for the piece with the cherry are:

If Julie takes 2, the odds that she has the cherry are doubled.

This reduces to .

Between the numbers 3 and 10, there are 8 numbers (3,4,5,6,7,8,9,10) and 3 prime numbers (3,5,7). 

Thus, the probability of selecting a prime number from the set is .

Given that Jacqueline is flipping a coin to help her make her decision as to what to wear, there is a  that she will decide to wear a red dress and a  chance that she will decide to wear flats. In order to find the chance of her wearing both of these items, we multiply the fractions together. This results in:

Given that Jenny can only remember where 2 of her gifts came from, and that she had 6 friends give her gifts, the chance that she will remember what Julie gave her is , which is equal to .

Probability is defined as the number of opportunities for a specific outcome (in this instance the number of black marbles) divided by the total number of outcomes (total number of marbles).