Answer:
see explanation
Step-by-step explanation:
Simplify the radical
=
=
Square both sides
T² = ( multiply both sides by (g + f) )
T²(g + f) = Ufg ( distribute left side )
T²g + T²f = Ufg ← subtract Ufg from both sides
T²g - Ufg + T²f = 0 ← subtract T²f from both sides
T²g - Ufg = - T²f ← factor out g from each term on the left side
g(T² - Uf) = - T²f ← divide both sides by (T² - Uf)
g = - =
Answer:
There is a probability of P=0.94 that at least 81 rolls are needed to get the sum of 307.
Step-by-step explanation:
The roll of a six-sided die sum has this parameters:
Mean: 3.5
Standard deviation: 1.7
If the die is rolled 81 times, the distribution of the sum of the 81 rolls will have the following parameters:
Note: the variance of the sum of random variables is equal to the sum of the variance of the individual variables.
Then, we can calculate the probabilties that the sum of 81 rolls is lower than 307.
There is 94% of chances that the sum of 81 rolls is lower than 307, so there is a probability of P=0.94 that at least 81 rolls are needed to get the sum of 307.