Two numbers are the ratio of 2:7. their sum is 63. what is the larger number?
2 answers:
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Answer:
a) Expected score on the exam is 12.8.
b) Variance 10.24, Standard deviation 3.2
Step-by-step explanation:
For each question, there are only two possible outcomes. Either you guesses the answer correctly, or you does not. The probability of guessing the answer of a question correctly is independent of other questions. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
Probability of exactly x sucesses on n repeated trials, with p probability.
The expected value of the binomial distribution is:
The variance of the binomial distribution is:
The standard deviation of the binomial distribution is:
64 questions.
So
5 possible answers, one correctly, chosen at random:
So
(a) What is your expected score on the exam?
(b) Compute the variance and standard deviation of x. Variance =Standard deviation
Variance 10.24
Standard deviation 3.2
After 85 minutes of calls, there are $27.25 left on the card.
<h3>What is the remaining credit after 85 minutes of calls?</h3>
A linear equation in slope-intercept form is:
y = a*x + b
Where a is the slope.
If the line passes through two points (x₁, y₁) and (x₂, y₂) the slope is:
In this case, we know that the line passes through the points (22, 36.7) and (52, 32,20)
(points of the form (time, dollars)).
So the slope is:
The linear equation is then:
y = -0.15*x + b
To find the value of b, we use the point (22. 36.7)
36.7 = -0.15*22 + b
36.7 + 0.15*22 = b = 40
Then the linear equation is:
y = -0.15*x +40
The amount remaining in the credit card after 85 minutes is given by evaluating the above equation in x = 85.
y = -0.15*85 + 40 = 27.25
This means that after 85 minutes of calls, there are $27.25 left on the card.
If you want to learn more about linear equations:
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