Free brainliest timmmmmmme :)

An observer (O) is located 900 feet from a building (B). The observer notices a helicopter (H) flying at a 49° angle of elevatio

Firdavs [7]

Answer:

1035.33 feet

Step-by-step explanation:

h=900tan49

=1035.33 feet

I hope it helps

6 0

2 years ago

According to the Bureau of Labor Statistics, students who have an after-school job spend an average of 42 fewer minutes per day

IgorLugansk [536]

Answer:

126 hrs

Step-by-step explanation:

-Given the school year has 180 days and the non-working student spends 42 minutes more than the working student.

-The total time during the school year is calculated as;

$Total Time=Time/day \times No \ of \ Days\\\\=42\ minutes \times 180\\\\=7560\ minutes$

We convert our calculated time in hour(1hr=60 minutes):

$=\frac{7560\ mins}{60\ mins}\\\\=126\ hrs$

Hence, the average non-working spends an average of 126 hrs that the working student.

4 0

2 years ago

Police use a radar unit is used to measure speeds of cars on a freeway. The speeds are normally distributed with a mean of 90 km

vagabundo [1.1K]

Answer:

A. P(x≥100)=0.1587

B. P(x≤0)≈0

Step-by-step explanation:

A. Cause we know the distribution of the data, the method used to solve it is called "Normalization" and we need to have the Mean and the Standard deviation of the data. The method consist in the following equation

P(x≤a)=P( z=((x-μ)/σ) ≤ b=((a-μ)/σ) )

Considering μ as the Mean and σ as the Standard deviation. At first, we had a probability in the normal distribution with Mean=90 and STD=10 but that kind of exercises is not meant to find that probability directly but by using this process.

After we normalize the probability, now we have a probability in a specific normal distribution that has Mean=0 and STD=1 and the difference with what we had before is that now we are able to use tools to find probabilities in a normal standard distribution. My favorite of them is a chart that show the approximate values of a lot of probabilities (i attached it to this answer). I´m going to explain point A as an example:

We look for the probability that P(x≥100), but we don´t have an easy method to use there, so we normalize:

P(x≥100)=P( (x-μ)/σ ≥ (100-μ)/σ )

P(x≥100)=P( z ≥ (100-90)/10 )

P(x≥100)=P( z ≥ 1 )

And now we are able to use the chart, let me explain: First, the chart only works with P(z ≤ b), so we have to change it with properties of probabilities before using the table.

P(z≥1)=1-P(z≤1)

And finally we use the chart:

the value of P(z≤1) is in the table, we look for the row with +1 and the column with the decimal part (in this case 0) and with coordinates (1,0) there´s the value:

P(z≤1)=0.8413

But we need P(z≥1) so we use the previous equality

P(z≥1)=1-P(z≤1)

P(z≥1)=1-0.8413

P(z≥1)=0.1587

Because P(x≥100)=P(z≥1), our final answer is 0.1587

B. We use the same process to try to understand what the probability of P(x≤0) represents.

P(x≤0)=P(z≤ (0-90)/10)

P(x≤0)=P( z ≤ -9 )

But when we try to look for its value in the chart It isn´t even there, what could it mean?

A normal distribution function is always increasing, that means that "a≤b if and only if P(x≤a) ≤ P(x≤b)". so we conclude:

P(z≤-9) ≤ P(z≤-3) (The lowest probability in the chart)

P(z≤-9) ≤ 0.0013

P(z≤-9) is way lower than 0.0013 (they aren´t even close) but we know that probability is always positive, and because of that:

P(x≤0)=P(z≤-9)≈0

5 0

2 years ago

A point moves in the plane in the following sequence.

dem82 [27]

Answer:

D

Step-by-step explanation:

The answer is point D(-2,1).

1. If the point D was moved down 2 units, then its coordinates became (-2,-1).

2. If point (-2,-1) was reflected over the x-axis, then its coordinates became (-2,1).

3. If the point (-2,1) was moved 4 units to the right, then its coordinates became (2,1).

4. If point (2,1) was reflected over y-axis, its coordinates became (-2,1).

4 0

2 years ago

George is considering two different investment options. The first option offers 7.4% per year simple interest on the

jok3333 [9.3K]

Answer:

Part A: The value of the simple interest investment at the end of three years is $12,220

Part B: The value of the compounded quarterly interest investment at the end of three years is $12,134.08

Part C: The simple interest investment is better over the first three years

Part D: I advise George to invest his money in the compounded interest investment if he will keep the money for a long time

Step-by-step explanation:

Part A:

A = P + P r t, where

A represents the value of the investment
P represents the original amount
r represents the rate in decimal
t represents the time in years

∵ George deposits $10,000

∴ P = 10,000

∵ First option offers 7.4% per year simple interest

∴ r = 7.4% = 7.4 ÷ 100 = 0.074

∵ He may not withdraw any of the money for three years after

the initial deposit

∴ t = 3

- Substitute all of these values in the formula above

∴ A = 10,000 + 10,000(0.074)(3)

∴ A = 10,000 + 2,220

∴ A = 12,220

The value of the simple interest investment at the end of three years is $12,220

Part B:

$A=P(1+\frac{r}{n})^{nt}$ , where

A represents the value of the investment
P represents the original amount
r represents the rate in decimal
n is a number of periods of a year
t represents the time in years

∵ George deposits $10,000

∴ P = 10,000

∵ The second option offers a 6.5% interest rate compounded quarterly

∴ r = 6.5% = 6.5 ÷ 100 = 0.065

∴ n = 4 ⇒ quarterly

∵ He may not withdraw any of the money for three years after

the initial deposit

∴ t = 3

- Substitute all of these values in the formula above

∴ $A=10,000(1+\frac{0.065}{4})^{(4)(3)}$

∴ $A=10,000(1.01625)^{12}$

∴ A = 12,134.08

The value of the compounded quarterly interest investment at the end of three years is $12,134.08

Part C:

∵ 12,220 > 12,134.08

∴ The simplest interest investment is better than the compounded

interest investment at the end of three years

The simple interest investment is better over the first three years

Part D:

I advise George to invest his money in the compounded interest investment if he will keep the money for a long time

Look to the attached graph below

The red line represents the simple interest investment
The blue curve represents the compounded interest investment
(Each 1 unit in the vertical axis represents $1000)
After 0 years and before 4.179 years the red line is over the blue curve, that means the simple interest is better because it gives more money than the compounded interest
After that the blue curve is over the red line that means the compounded quarterly is better because it gives more money than the simple interest

4 0

2 years ago