Answer:
The probability that a baby born with Down's syndrome is a boy is
.
Step-by-step explanation:
The probability of a baby born being a boy (B) or a girl (G) is same, i.e.
P (B) = P (G) = 0.50.
The probability of a boy is born with Down's syndrome is, P (D|B) = <em>p</em>.
The probability of a girl is born with Down's syndrome is, P (D|G) = <em>q</em>.
The law of total probability states that:
![P(X)=P(X|Y)P(Y)+P(X|Z)P(Z)](https://tex.z-dn.net/?f=P%28X%29%3DP%28X%7CY%29P%28Y%29%2BP%28X%7CZ%29P%28Z%29)
Use this law to compute the probability of a baby born with Down's syndrome as follows:
![P(D)=P(D|B)P(B)+P(D|G)P(G)\\=(p\times0.50)+(q\times0.50)\\=0.50(p+q)](https://tex.z-dn.net/?f=P%28D%29%3DP%28D%7CB%29P%28B%29%2BP%28D%7CG%29P%28G%29%5C%5C%3D%28p%5Ctimes0.50%29%2B%28q%5Ctimes0.50%29%5C%5C%3D0.50%28p%2Bq%29)
The conditional probability of an event <em>X</em> given that another event <em>Y</em> has already occurred is:
![P(X|Y)=\frac{P(Y|X)P(X)}{P(Y)}](https://tex.z-dn.net/?f=P%28X%7CY%29%3D%5Cfrac%7BP%28Y%7CX%29P%28X%29%7D%7BP%28Y%29%7D)
Compute the probability that a baby born with Down's syndrome is a boy as follows:
![P(B|D)=\frac{P(D|B)P(B)}{P(D)} =\frac{p\times0.50}{0.50(p+q)} =\frac{p}{p+q}](https://tex.z-dn.net/?f=P%28B%7CD%29%3D%5Cfrac%7BP%28D%7CB%29P%28B%29%7D%7BP%28D%29%7D%20%3D%5Cfrac%7Bp%5Ctimes0.50%7D%7B0.50%28p%2Bq%29%7D%20%3D%5Cfrac%7Bp%7D%7Bp%2Bq%7D)
Thus, the probability that a baby born with Down's syndrome is a boy is
.
Hello.
In order to find the percentage of the questions that were correct, we need to find the decimal value of 64/75.
64/75 = 0.853...
To convert decimals to percentages, you multiply the decimal by 100.
0.853... x 100 = 85.33..%
The percent of the questions that were correct is about 85.3%.
<span> 20% of 40 is 8. so 40</span>
Think money
If you owe your mom 75 dollars, from your point of view you have - 75 dollars.
You go for a walk in the park and find a 50 dollar bill. There's no one around, so you decide to keep it. If you intend to pay your mom back, where are you? From your point of view you just have + 50 dollars to offset that - 75. Add them together.
- 75 + 50 = -25 You are still in negative territory, but you owe your mom a lot less than you did before you went for a walk.