So you have a 50% chance to have a boy vs a girl (1/2). If you want 3 children, that would be 1/3*1/2= 1/6 or 16.67% chance
W = white keys
b = black keys
w + b = 88
We know the number of black keys, it is 36
w + 36 = 88
w + 36 - 36 = 88 - 36
w = 52
So, the number of white keys is 52.
Now, we can write the ratio.
It would be :
b : w
36 : 52
Let's simplify . . .
They are both divisible by 4:
36/4 : 52/4
Simplifies to . . .
9 : 13
So, the ratio is 9 black keys: 13 white keys.
Final Answer: 9 black keys : 13 white keys
*I looked to see if this was actually true on a real piano, and it was!
Here is the correct computation of the question.
The future lifetimes (in months) of two components of a machine have the following joint density function:
for 0 < x < 50 - y < 50, otherwise.
Write down a single integral representing the probability that both components are still functioning in 20 months from now.
Answer:
Step-by-step explanation:
From the given information;
for 0 < x < 50 - y < 50, otherwise.
We can assert that the probability is the integral of the given density over the part of the range 0 ≤ x ≤ 50 - y ≤ 50 in which both x and y are greater than 20.
From the attached file below; their shows a probability density graph illustrating the above statement being said.
Now; to determine the probability that illustrates the integral of the density ; we have : P[(X > 20)∩(Y > 20)]
In addition to that:
From the image attached below;
We look into the region where the joint density under study is said to be positive and the triangle limits by the line axis x+y = 50
∴
Thus; the single integral representing the probability that both components are still functioning in 20 months from now is