That's OK, but you have not said which variable you want to solve it for.

To solve for 'x':
 c + ax = dx

Subtract c from each side: ax = dx - c

Subtract dx from each side: ax - dx = -c

Factor the left side: x (a - d) = -c

Divide each side by (a - d) : x = -c / (a - d) or x = c / (d - a) .

To solve for 'c': 
 c + ax = dx

Subtract ax from each side and factor: c = x (d - a) 

To solve for 'd': 
 c + ax = dx

Divide each side by 'x': d = c/x + a .

To solve for 'a':
 c + ax = dx

Subtract 'c' from each side: ax = dx - c

Divide each side by 'x': a = d - c/x .
.

6 0

2 years ago

The proportion of U.S. births that result in a birth defect is approximately 1/33 according to the Centers for Disease Control a

Dafna11 [192]

Answer:

Probability that at least 490 do not result in birth defects = 0.1076

Step-by-step explanation:

Given - The proportion of U.S. births that result in a birth defect is approximately 1/33 according to the Centers for Disease Control and Prevention (CDC). A local hospital randomly selects five births and lets the random variable X count the number not resulting in a defect. Assume the births are independent.

To find - If 500 births were observed rather than only 5, what is the approximate probability that at least 490 do not result in birth defects

Proof -

Given that,

P(birth that result in a birth defect) = 1/33

P(birth that not result in a birth defect) = 1 - 1/33 = 32/33

Now,

Given that, n = 500

X = Number of birth that does not result in birth defects

Now,

P(X ≥ 490) = $\sum\limits^{500}_{x=490} {^{500} C_{x} } (\frac{32}{33} )^{x} (\frac{1}{33} )^{500-x}$

= ${^{500} C_{490} } (\frac{32}{33} )^{490} (\frac{1}{33} )^{500-490}$ + .......+ ${^{500} C_{500} } (\frac{32}{33} )^{500} (\frac{1}{33} )^{500-500}$