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3 years ago

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Sarah predicts that 15 percent of all the birds she spots while bird watching will be robins. At the end of the day, she records

that 10 out of the 25 birds she spotted were robins. How does Sarah’s prediction compare with the actual results?

1 answer:

Mashutka [201]3 years ago

8 0

We can turn the probability 10 out of 25 as percentage

$\frac{10}{25}$ ×100=40%

The actual result is higher than prediction

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The cheerleading team is doing a car wash for a fundraiser. They are able to wash an average of 1 1/2 cars each 1/6 hour. What i

Mrrafil [7]

Answer:

9 cars/hour

Step-by-step explanation:

1.5 cars=1/6 hours

multiply both by 6

9 cars=1 hour

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A formula for finding P, the perimeter of a rectangle, is P = 2l + 2w, where l is the length of the rectangle, and w is its widt

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Answer:

P=30cm

Step-by-step explanation:

So the formula there is to find the Perimeter of the rectangle, so we are going to use it!

Using Substitution:

$A=2L+2W\\A=2(10)+2(5)\\A=20+10\\A=30$

Hope this helps!

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3 years ago

When hired at a new job selling jewelry, you are given two pay options:

Savatey [412]

Answer:

Option a because you will make more orofits

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3 years ago

Although cities encourage carpooling to reduce traffic congestion, most vehicles carry only one person. For example, 64% of vehi

ira [324]

Answer:

a) 0.7291 is the probability that more than half out of 10 vehicles carry just 1 person.

b) 0.996 is the probability that more than half of the vehicles carry just one person.

Step-by-step explanation:

We are given the following information:

A) Binomial distribution

We treat vehicle on road with one passenger as a success.

P(success) = 64% = 0.64

Then the number of vehicles follows a binomial distribution, where

$P(X=x) = \binom{n}{x}.p^x.(1-p)^{n-x}$

where n is the total number of observations, x is the number of success, p is the probability of success.

Now, we are given n = 10

We have to evaluate:

$P(x \geq 6) = P(x =6) +...+ P(x = 10) \\= \binom{10}{6}(0.64)^6(1-0.64)^4 +...+ \binom{10}{10}(0.64)^{10}(1-0.79)^0\\=0.7291$

0.7291 is the probability that more than half out of 10 vehicles carry just 1 person.

B) By normal approximation

Sample size, n = 92

p = 0.64

$\mu = np = 92(0.64) = 58.88$

$\sigma = \sqrt{np(1-p)} = \sqrt{92(0.64)(1-0.64)} = 4.60$

We have to evaluate the probability that more than 47 cars carry just one person.

$P(x \geq 47)$

After continuity correction, we will evaluate

$P( x \geq 46.5) = P( z > \displaystyle\frac{46.5 - 58.88}{4.60}) = P(z > -2.6913)$

$= 1 - P(z \leq -2.6913)$

Calculation the value from standard normal z table, we have,

$P(x > 46.5) = 1 - 0.004 = 0.996 = 99.6\%$

0.996 is the probability that more than half out of 92 vehicles carry just one person.

5 0

3 years ago

A demographer wants to measure life expectancy in countries 1 and 2. Let μ1 and μ2 denote the mean life expectancy in countries

Art [367]

Answer:

For this case we want to test if life expectancy in country 1 is more than 10 years lower than in country 2, (alternatibe hypothesis), so then the system of hypothesis are:

Null hypothesis: $\mu_1 \leq \mu_2 -10$

Alternative hypothesis: $\mu_1 > \mu_2 -10$

Or equivalently:

Null hypothesis: $\mu_1 - \mu_2 \leq 10$

Alternative hypothesis: $\mu_1 - \mu_2 >10$

Step-by-step explanation:

Previous concepts

A hypothesis is defined as "a speculation or theory based on insufficient evidence that lends itself to further testing and experimentation. With further testing, a hypothesis can usually be proven true or false".

The null hypothesis is defined as "a hypothesis that says there is no statistical significance between the two variables in the hypothesis. It is the hypothesis that the researcher is trying to disprove".

The alternative hypothesis is "just the inverse, or opposite, of the null hypothesis. It is the hypothesis that researcher is trying to prove".

Solution to the problem

For this case we want to test if life expectancy in country 1 is more than 10 years lower than in country 2, (alternatibe hypothesis), so then the system of hypothesis are:

Null hypothesis: $\mu_1 \leq \mu_2 -10$

Alternative hypothesis: $\mu_1 > \mu_2 -10$

Or equivalently:

Null hypothesis: $\mu_1 - \mu_2 \leq 10$

Alternative hypothesis: $\mu_1 - \mu_2 >10$

7 0

3 years ago