Explain how I get the answer to 5^2-(5-7)(2)
2 answers:
You might be interested in
Answer:
The sum of reciprocals is 2/3.
You don't need complex numbers to solve this, but if you try to find a and b you will need complex numbers.
Step-by-step explanation:
a+b = 2
a*b = 3
1/a + 1/b = x
(a*b)*(1/a + 1/b) = (a*b)x
b + a = (a*b)(x)
2 = 3x
x = 2/3
b = 2 - a
a*(2 - a) = 3
-a^2 + 2a = 3
-a^2 + 2a - 3 = 0
a^2 - 2a + 3 = 0
let's solve the quadratic equation
a^2 - 2a + 3 = a^2 - 2a + 1 + 2 = (a - 1)^2 + 2 = 0
(a - 1)^2 = -2
these options correspond to a and b from the original question.
Answer:
17.5%
Step-by-step explanation:
First of all, see this situation as a cumulative binomial distribution. You have isolated trials with a probability of success. This makes it binomial. The wording of the question "what is the probability of at least half..." makes this cumulative.
There are a few ways to calculate this, and I'm not quite sure which way you're familiar with. I'll show the cumbersome way and use wolfram to make the calculation.
First, I'll calculate the probability for 15 success, given 30 trials.
30c15*0.4^15*0.6^15
Since the question asks for the probability of at least 15 success, I'll have to make a calculation for the probability of 16 successes, then 17, and so on. Then I'll have to add all the probabilities together. So, I'll use wolfram for that (see attached)
