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In this lesson, we will learn how to calculate conditional probability.

Q1:

In the final exam, 5 5 % of students failed chemistry, 2 5 % failed physics and 1 6 % failed both. What is the probability that a student passed physics given that they passed chemistry?

Q2:

Victoria either takes the bus to school or, if she misses it, she walks. The probability that she catches the bus on any given day is 0.4. If she catches the bus, the probability that she will get to school on time is 0.8, but if she misses the bus and has to walk, the probability of her being on time drops to 0.6.

Work out the probability that she catches the bus and is on time for school on a given day.

Work out the probability that she is on time for school on a given day, whether or not she catches the bus.

Hence, find the probability that she will be late for school on a given day.

Q3:

Anthony rolled two six-sided dice and added the two numbers.

Determine the probability of obtaining a score of 7.

Determine the probability of obtaining a score of 7 given that at least one three is rolled.

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