Given:
Number of red marbles = 5
Number of blue marbles = 4
Number of yellow marbles = 3
To find:
The probability of pulling a red marble, then pulling a blue marble, without replacement.
Solution:
Probability formula:

We have,
Number of red marbles = 5
Total number of marbles is:

Probability of getting a red marble is:

After selecting one red marble, the remaining number of marbles is 11 and the number of blue marbles is 3. So,

Now, the probability of pulling a red marble, then pulling a blue marble, without replacement is:




Therefore, the correct option is B.
No look at the problem set as a fraction Jed did 2 shots in 5 seconds while simplified Alex shot 1 every 3 seconds . hope this helps
Systematic sampling is a type of probability sampling method in which sample members from a larger population are selected according to a random starting point but with a fixed, periodic interval. This interval, called the sampling interval, is calculated by dividing the population size by the desired sample size.
54=.9x Solve for x. x=54/.9=60