The sum of 7 2/9 and 2 7/9 in the simplest form is

In a study, researchers found that for every 3 people who preferred band A toothpaste 1 person preferred band B toothpaste. Whic

oksian1 [2.3K]

C) 3:1

For every 3 people who prefer band A toothpaste 1 person preferred band B toothpaste:

3 to 1=3:1.

8 0

3 years ago

Jane must get at least three of the four problems on the exam correct to get an A. She has been able to do 80% of the problems o

NISA [10]

Answer:

a) There is n 81.92% probability that she gets an A.

b) If she gets the first problem correct, there is an 89.6% probability that she gets an A.

Step-by-step explanation:

For each question, there are only two possible outcomes. Either the answer is correct, or it is not. This means that we can solve this problem using binomial distribution probability concepts.

Binomial probability distribution

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

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

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 $\pi$ is the probability of X happening.

For this problem, we have that:

The probability she gets any problem correct is 0.8, so $\pi = 0.8$ .

(a) What is the probability she gets an A?

There are four problems, so $n = 4$

Jane must get at least three of the four problems on the exam correct to get an A.

So, we need to find $P(X \geq 3)$

$P(X \geq 3) = P(X = 3) + P(X = 4)$

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

$P(X = 3) = C_{4,3}.(0.80)^{3}.(0.2)^{1} = 0.4096$

$P(X = 4) = C_{4,4}.(0.80)^{4}.(0.2)^{0} = 0.4096$

$P(X \geq 3) = P(X = 3) + P(X = 4) = 2*0.4096 = 0.8192$

There is n 81.92% probability that she gets an A.

(b) If she gets the first problem correct, what is the probability she gets an A?

Now, there are only 3 problems left, so $n = 3$

To get an A, she must get at least 2 of them right, since one(the first one) she has already got it correct.

So, we need to find $P(X \geq 2)$

$P(X \geq 3) = P(X = 2) + P(X = 3)$

$P(X = 2) = C_{3,2}.(0.80)^{2}.(0.2)^{1} = 0.384$

$P(X = 4) = C_{3,3}.(0.80)^{3}.(0.2)^{0} = 0.512$

$P(X \geq 3) = P(X = 2) + P(X = 3) = 0.384 + 0.512 = 0.896$

If she gets the first problem correct, there is an 89.6% probability that she gets an A.

3 0

3 years ago

A rectangular swimming pool is twice as long as it is wide. A small concrete sidewalk surrounds the pool and is a constant 2 fee

Naddika [18.5K]

Answer:

The dimensions of the pool are:

Width: 8.944 feet

Length: 17.888 feet

Step-by-step explanation:

From Geometry, the area of a rectangle ( $A$ ), measured in square feet, is determined by the following equations:

$A = w\cdot l$ (1)

Where:

$w$ - Width, measured in feet.

$l$ - Length, measured in feet.

If we know that $w = x$ , $l = 2\cdot x$ and $A = 160\,ft^{2}$ , then we get the following second order polynomial:

$2\cdot x^{2}-160 = 0$ (1)

And we solve the expression for $x$ :

$2\cdot x^{2} = 160$

$x^{2} = 80$

$x = \sqrt{80}\,ft$

$x \approx 8.944\,ft$

Then, the dimensions of the pool are, respectively:

$w \approx 8.944\,ft$ and $l \approx 17.888\,ft$

5 0

2 years ago

Of the 200 packages of bagels sold 15 of them are sesame seed bagels what percent of the bagel packages sold are sesame seed bag

Shalnov [3]

15 = x% from 200
15 = * 200
15 = 2x / ÷ 2 (both sides)
x = 7.5 [percent]

6 0

3 years ago

Read 2 more answers

Help

Vedmedyk [2.9K]

By pythagoreans' theorem,

Longer edge
= √(2² + 6²)
= √40

∴ The length of the longer edge is the square root of 40 feet.

Shorter edge
= √(1² + 3²)
= √10

Area = L × B
= √40 × √10
= 20 feet²

8 0

3 years ago

Read 2 more answers