All categories

3 years ago

Emma is building wall around

Mathematics

2 answers:

inessss [21]3 years ago

8 0

It will take 60 minutes, 1 hour

liq [111]3 years ago

8 0

Write and solve an equation of ratios:

75% 45 min
-------- = -----------
100% x

75x = 4500, and x = 60 (minutes)

You might be interested in

USA Today reports that about 25% of all prison parolees become repeat offenders. Alice is a social worker whose job is to counse

pychu [463]

Answer:

a) $P(X=0)=(4C0)(0.75)^0 (1-0.75)^{4-0}=0.0039$

$P(X=1)=(4C1)(0.75)^1 (1-0.75)^{4-1}=0.0469$

$P(X=2)=(4C2)(0.75)^2 (1-0.75)^{4-2}=0.211$

$P(X=3)=(4C3)(0.75)^2 (1-0.75)^{4-3}=0.422$

$P(X=4)=(4C4)(0.75)^2 (1-0.75)^{4-4}=0.316$

b) $E(X) = np = 4*0.75=3$

c) $Sd(X) =\sqrt{np(1-p)}=\sqrt{4*0.75*(1-0.75)}=0.866$

d) $P(X \geq 3) \geq 0.98$

And the dsitribution that satisfy this is $X\sim Binom(n=9,p=0.75$

Step-by-step explanation:

Previous concepts

The binomial distribution is a "DISCRETE probability distribution that summarizes the probability that a value will take one of two independent values under a given set of parameters. The assumptions for the binomial distribution are that there is only one outcome for each trial, each trial has the same probability of success, and each trial is mutually exclusive, or independent of each other".

Let X the random variable of interest, on this case we now that:

$X \sim Binom(n=4, p=1-0.25=0.75)$

The probability mass function for the Binomial distribution is given as:

$P(X)=(nCx)(p)^x (1-p)^{n-x}$

Where (nCx) means combinatory and it's given by this formula:

$nCx=\frac{n!}{(n-x)! x!}$

Part a

$P(X=0)=(4C0)(0.75)^0 (1-0.75)^{4-0}=0.0039$

$P(X=1)=(4C1)(0.75)^1 (1-0.75)^{4-1}=0.0469$

$P(X=2)=(4C2)(0.75)^2 (1-0.75)^{4-2}=0.211$

$P(X=3)=(4C3)(0.75)^2 (1-0.75)^{4-3}=0.422$

$P(X=4)=(4C4)(0.75)^2 (1-0.75)^{4-4}=0.316$

Part b

The expected value is givn by:

$E(X) = np = 4*0.75=3$

Part c

For the standard deviation we have this:

$Sd(X) =\sqrt{np(1-p)}=\sqrt{4*0.75*(1-0.75)}=0.866$

Part d

For this case the sample size needs to be higher or equal to 9. Since we need a value such that:

$P(X \geq 3) \geq 0.98$

And the dsitribution that satisfy this is $X\sim Binom(n=9,p=0.75$

We can verify this using the following code:

"=1-BINOM.DIST(3,9,0.75,TRUE)" and we got 0.99 and the condition is satisfied.

4 0

3 years ago

Working as a team 8 mathletes can solve 20 problems in ten minutes. At this same rate how many mathletes are needed in order to

emmainna [20.7K]

7 is the right answer(please rate 5.0 stars so i can help other people out thanks)

8 0

3 years ago

Read 2 more answers

The area of the entire large rectangle

Luda [366]

There is no rectangle but the formula is

$a = l \times w$

5 0

3 years ago

22 pencils divided by three people evenly

Morgarella [4.7K]

It wouldnt be an even number but i got 7.3

8 0

3 years ago

the area of a bathroom floor measures 3 yards by 3 yards and each custom tile that makes up the flooring is 1 1/2 square yards.

wel

Using the area, the number of tiles needed to cover the floor is 6.

The area is the region bounded by the shape of an object.

Therefore, the bathroom floor measures 3 yards by 3yards.

Hence the area of the bathroom floor can be calculated as follows;

area of the bathroom floor = 3 × 3

area of the bathroom floor = 9 yards²

The area of the custom tiles that makes the flooring is 1 1 /2 square yards.

Hence,

number of tiles needed to cover the floor = 9 ÷ 3 /2

number of tiles needed to cover the floor = 9 × 2 / 3

number of tiles needed to cover the floor = 18 / 3

number of tiles needed to cover the floor = 6

learn more on area here: brainly.com/question/946354

#SPJ1

4 0

1 year ago