Step 1. READ THE QUESTION CAREFULLY!!!!!!
Step 2. Turn the problem into equations.
Step 3. Substitute/Eliminate variables.
Step 4. Find the first variable.
Step 5. Replace the variable1 with its correct number.
Step 6. Get your variable2.
Step 7.Do steps 3-4 until you have all the variables.
Step 8. Double check.
And you are done!
It's really important that you aim to understand how to do these problems yourself, rather than "pay" others to do them for you. Why not ask for "directions" or "guidance," instead of for "answers?"
This is a tricky question because it's not required that you have the full 12 beads on the string in every case. You could, for example, have 6 beads, 2 of which would be red, making the ratio of red beads 2 to 6, or 1 to 3.
What about 3 red beads in 9?
What about 1 red bead in 3?
Do these "answers" satisfy the requirement that the ratio of red beads to all beads is 1:3?
4r^2=4 if r=1
2s^3=250 if s=5
Answer: The required probability is 0.334.
Step-by-step explanation:
Since we have given that
N = 15 reservations
probability of reservations will not be used = 0.2
probability of reservations will be used = 1-0.2=0.8
Let X be the Binomial variable,that the number of reservations canceled.
We need to find the probability that more than 8 but less than 12 reservations.
So, it becomes,

Hence, the required probability is 0.334.