Question

The probability of a student getting an A....

Answer 1

Answer:

$P (M\ and\ C) = \frac{1}{4}=25\%$

Step-by-step explanation:

We call M the event in which a student gets an A in math and we call C the event in which a student gets an A in chemistry. As the events are not mutually exclusive, then.

$P (M\ or\ C) = P (M) + P (C) - P (M\ and\ C)$

In this case we know that:

$P (M\ or\ C) = \frac{7}{10}$

$P (M) =\frac{17}{20}$

$P (C) =\frac{1}{10}$

So

$P (M\ and\ C) = P (M) + P (C) - P (M\ or\ C)$

$P (M\ and\ C) = \frac{17}{20} + \frac{1}{10} -\frac{7}{10}$

$P (M\ and\ C) = \frac{1}{4}$