a) To find π(πΈπ£ππ | πΊππππ‘ππ π‘βππ 30), we first find the total number of even numbers between 10 and 40 (inclusive). The even numbers between 10 and 40 are {10, 12, 14, ..., 38, 40}, which is a total of 16 numbers.
The numbers greater than 30 are {31, 32, ..., 40}, which is a total of 10 numbers. Out of these, the even numbers are {32, 34, 36, 38, 40}, which is a total of 5 numbers.
Therefore, π(πΈπ£ππ | πΊππππ‘ππ π‘βππ 30) = \frac{5}{10} = \frac{1}{2} .
b) To find π(πΊππππ‘ππ π‘βππ 30 | πΈπ£ππ), we first find the total number of even numbers between 10 and 40 (inclusive), which is 16.
The number of even numbers greater than 30 is 5 as found in part (a).
Therefore, π(πΊππππ‘ππ π‘βππ 30 | πΈπ£ππ) = \frac{5}{16} .
c) To find π(πππππ | π΅ππ‘π€πππ 20 πππ 30), we need to find the prime numbers between 20 and 30. The prime numbers between 20 and 30 are {23, 29}, which is a total of 2 numbers.
The numbers between 20 and 30 (inclusive) are {20, 21, ..., 30}, which is a total of 11 numbers.
Therefore, π(πππππ | π΅ππ‘π€πππ 20 πππ 30) = \frac{2}{11} .
\textbf{Answer:}
a) \frac{1}{2}
b) \frac{5}{16}
c) \frac{2}{11}