Answer:
Step-by-step explanation:
A circumference of a circle can be determined by this: 2*pi*r
We're given the diameter. Divide that by 2 to get the radius.
6.45/2 = 3.225
Now multiply that by 2*pi. That gives us 2 * 3.14 * 3.225 = 20.253.
This could've also been done easier by doing pi*d where d is the diameter and you give the answer by multiplying them both. Also works, but the above formula is just key to many things and can also be used to derive the simpler one. Hope it helps! :)
Answer:
Step-by-step explanation:
We know that:
In a deck of 52 cards there are 4 aces.
Therefore the probability of obtaining an ace is:
P (x) = 4/52
The probability of not getting an ace is:
P ('x) = 1-4 / 52
P ('x) = 48/52
In this problem the number of aces obtained when extracting cards from the deck is a discrete random variable.
For a discrete random variable V, the expected value is defined as:
Where V is the value that the random variable can take and P (V) is the probability that it takes that value.
We have the following equation for the expected value:
In this problem the variable V can take the value V = 9 if an ace of the deck is obtained, with probability of 4/52, and can take the value V = -1 if an ace of the deck is not obtained, with a probability of 48 / 52
Therefore, expected value for V, the number of points obtained in the game is:
So: