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3 years ago

there are 390 students at a school if each classroom holds 30 students how many classroom are needed at the school?

Mathematics

2 answers:

enot [183]3 years ago

7 0

Answer:

Step-by-step explanation:

390 divided by 30 equals 13

drek231 [11]3 years ago

6 0

Answer:

the school need 13 classrooms

Step-by-step explanation:

390:30=13

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3 years ago

The probability that a single radar station will detect an enemy plane is 0.65.

taurus [48]

Answer:

a) We need 4 stations to be 98% certain that an enemy plane flying over will be detected by at least one station.

b) If seven stations are in use, the expected number of stations that will detect an enemy plane is 4.55.

Step-by-step explanation:

For each station, there are two two possible outcomes. Either they detected the enemy plane, or they do not. This means that we can solve this problem using concepts of the binomial probability distribution.

Binomial probability distribution

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

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

In which $C_{n,x}$ is the number of different combinatios 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:

The probability that a single radar station will detect an enemy plane is 0.65. This means that $n = 0.65$ .

(a) How many such stations are required to be 98% certain that an enemy plane flying over will be detected by at least one station?

This is the value of n for which $P(X = 0) \leq 0.02$ .

n = 1.

$P(X = 0) = C_{1,0}.(0.65)^{0}.(0.35)^{1} = 0.35$

n = 2

$P(X = 0) = C_{2,0}.(0.65)^{0}.(0.35)^{2} = 0.1225$

n = 3

$P(X = 0) = C_{3,0}.(0.65)^{0}.(0.35)^{3} = 0.0429$

n = 4

$P(X = 0) = C_{4,0}.(0.65)^{0}.(0.35)^{4} = 0.015$

We need 4 stations to be 98% certain that an enemy plane flying over will be detected by at least one station.

(b) If seven stations are in use, what is the expected number of stations that will detect an enemy plane?

The expected number of sucesses of a binomial variable is given by:

$E(x) = np$

So when $n = 7$

$E(x) = 7*(0.65) = 4.55$

If seven stations are in use, the expected number of stations that will detect an enemy plane is 4.55.

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3 years ago

Write down three integers,all less than 25, whose range is 8, and mean is 11

MAXImum [283]

Answer:

6, 13 and 14

Step-by-step explanation:

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3 years ago

Question 9 of 10 What is the equation of the following line? Be sure to scroll down first to see all answer options. 10 110 (0,0

Papessa [141]

Answer:

C) $y=-\frac{1}{5}x$

Step-by-step explanation:

The equation of a straight line is given by:

y = mx + b

where m is the slope of the line, b is the y intercept (value of x when y is 0) and y, x are variables.

The equation of a line passing through two points (x₁, y₁) and (x₂, y₂) is given by:

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From the graph, the line passes through (0, 0) and (10, -2), hence the equation of the line is:

$y-0=\frac{-2-0}{10-0}(x-0)\\\\y=-\frac{1}{5}x \\\\$

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3 years ago

Write the point-slope form of the equation of the line through the given point with the given slope.

IrinaVladis [17]

Answer:

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3 years ago

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there are 390 students at a school if each classroom holds 30 students how many classroom are needed at the school?​

there are 390 students at a school if each classroom holds 30 students how many classroom are needed at the school?