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Dmitry [639]
3 years ago
5

A teacher is four times as old as a student. In 28 years, the student's age will be half of the teacher's age. How old are they

now?
The age of the teacher is
years.
The age of the student is
years
Mathematics
1 answer:
swat323 years ago
7 0
Here, let the age of student be x and teacher be 4x after 28 years, the teacher is double the age of student. So the age of teacher will be 4x+28 and student will be 2(x+28)
So,
4x+28=2(x+28)
4x+28=2x+56
4x-2x=56-28
2x=28
x=14
Therefore the age of the teacher in present will be
=4x+28
=4*14+28
=84
And age of student will be:
=x+28
=14+28
=42
Hope this helps


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Answer:

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b) 0.2977

c) 0.56

Step-by-step explanation:

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Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

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In which C_{n,x} is the number of different combinations of x objects from a set of n elements, given by the following formula.

C_{n,x} = \frac{n!}{x!(n-x)!}

And p is the probability of X happening.

In this problem we have that:

13 percent of the drivers stopped for speeding have invalid licenses.

This means that p = 0.13

14 drivers are stopped

This means that n = 14

(a) None will have an invalid license.

This is P(X = 0)

P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}

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(b) Exactly one will have an invalid license.

This is P(X = 1)

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(c) At least 2 will have invalid licenses.

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P(X < 2) + P(X \geq 2) = 1

We want P(X \geq 2)

So

P(X \geq 2) = 1 - P(X < 2)

In which

P(X < 2) = P(X = 0) + P(X = 1) = 0.1423 + 0.2977 = 0.44

P(X \geq 2) = 1 - P(X < 2) = 1 - 0.44 = 0.56

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