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A box contains slips with numbers from 1...

A box contains slips with numbers from 1 to 50 written on them. A slip is drawn and replaced. Then another slip is drawn and after replacing another slip is drawn. What is the probability that an even number appears on the first draw, an odd number on the second draw and a number divisible by 3 on the third draw?

A

`1/25`

B

`2/25`

C

`8/25`

D

`4/25`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we need to calculate the probability of drawing an even number first, an odd number second, and a number divisible by 3 third. We will follow these steps: ### Step 1: Calculate the probability of drawing an even number on the first draw. - **Total numbers from 1 to 50**: 50 - **Even numbers from 1 to 50**: 2, 4, 6, ..., 50 (which are 25 even numbers) The probability of drawing an even number is given by: \[ P(\text{Even}) = \frac{\text{Number of Even Numbers}}{\text{Total Numbers}} = \frac{25}{50} = \frac{1}{2} \] ### Step 2: Calculate the probability of drawing an odd number on the second draw. - **Odd numbers from 1 to 50**: 1, 3, 5, ..., 49 (which are also 25 odd numbers) The probability of drawing an odd number is given by: \[ P(\text{Odd}) = \frac{\text{Number of Odd Numbers}}{\text{Total Numbers}} = \frac{25}{50} = \frac{1}{2} \] ### Step 3: Calculate the probability of drawing a number divisible by 3 on the third draw. - **Numbers divisible by 3 from 1 to 50**: 3, 6, 9, ..., 48. To find how many numbers are divisible by 3, we can use the formula for the nth term of an arithmetic sequence: - First term (a) = 3 - Common difference (d) = 3 - Last term (l) = 48 To find the number of terms (n): \[ l = a + (n-1)d \implies 48 = 3 + (n-1) \cdot 3 \] \[ 48 - 3 = (n-1) \cdot 3 \implies 45 = (n-1) \cdot 3 \implies n-1 = 15 \implies n = 16 \] Thus, there are 16 numbers divisible by 3. The probability of drawing a number divisible by 3 is given by: \[ P(\text{Divisible by 3}) = \frac{\text{Number of Numbers Divisible by 3}}{\text{Total Numbers}} = \frac{16}{50} = \frac{8}{25} \] ### Step 4: Calculate the combined probability of all three events. Since the draws are independent (the slip is replaced each time), we multiply the probabilities: \[ P(\text{Even, Odd, Divisible by 3}) = P(\text{Even}) \cdot P(\text{Odd}) \cdot P(\text{Divisible by 3}) \] \[ = \frac{1}{2} \cdot \frac{1}{2} \cdot \frac{8}{25} = \frac{1 \cdot 1 \cdot 8}{2 \cdot 2 \cdot 25} = \frac{8}{100} = \frac{2}{25} \] ### Final Answer: The probability that an even number appears on the first draw, an odd number on the second draw, and a number divisible by 3 on the third draw is \(\frac{2}{25}\). ---
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