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1 year ago

A city that had 40,000 trees started losing them at a rate of 10 percent per year because of urbanization.

Mathematics

1 answer:

goblinko [34]1 year ago

7 0

Answer:

t = 13.1576 years

Step-by-step explanation:

The situation can be modeled as

P = Po.(1-r)^t

Where

t is the years transcurred

Po is the initial amount

r is the rate of change

Po = 40000

r = 10% equivalent to 0.1

Now

A quarter of the original amount

(1/4)*Po = Po.(1-r)^t

(1/4) = (0.9)^t

t = 13.1576

Please, see attached picture

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The Bay Area Online Institute (BAOI) has set a guideline of 60 hours for the time it should take to complete an independent stud

yarga [219]

Answer:

At the 5% level, BAOI can infer that the average time to complete does not exceeds 60 hours.

Step-by-step explanation:

From the question we are told that

The population mean is $\mu = 60 \ hr$

The sample size is $n = 16$

The sample mean is $\= x = 68 \ hr$

The standard deviation is $\sigma = 20 \ hr$

The null hypothesis is $H_o : \mu = 60$

The alternative $H_a : \mu > 60$

Here we would assume the level of significance of this test to be

$\alpha = 5\% = 0.05$

Next we will obtain the critical value of the level of significance from the normal distribution table, the value is $Z_{0.05} = 1.645$

Generally the test statistics is mathematically represented as

$t = \frac{ \= x - \mu}{ \frac{ \sigma }{\sqrt{n} } }$

substituting values

$t = \frac{ 68 - 60 }{ \frac{ 20 }{\sqrt{16} } }$

$t = 1.6$

Looking at the value of t and $Z_{\alpha }$ we see that $t< Z_{\alpha }$ hence we fail to reject the null hypothesis

This means that there no sufficient evidence to conclude that it takes more than 60 hours to complete the course

At the 5% level, BAOI can infer that the average time to complete does not exceeds 60 hours.

6 0

1 year ago

Angles BAE and FAC are straight angles. What angle relationship best describes angles BAC and DAC?

vova2212 [387]

Answer:

They are adjacent angles

Step-by-step explanation:

3 0

2 years ago

A student repeatedly measures the mass of an object using a mechanical balance and gets the following values: 560 g, 562 g, 556

MrRissso [65]

Answer: 2.76 g

Step-by-step explanation:

The formula to find the standard deviation:-

$\sigma=\sqrt{\dfrac{\sum(x_i-\overline{x})^2}{n}}$

The given data values : 560 g, 562 g, 556 g, 558 g, 560 g, 556 g, 559 g, 561 g, 565 g, 563 g.

Then, $\overline{x}=\dfrac{\sum_{i=1}^{10} x_i}{n}\\\\\Rightarrow\ \overline{x}=\dfrac{560+562+556+558+560+556+559+561+565+563}{10}\\\\\Rightarrow\ \overline{x}=\dfrac{5600}{10}=560$

Now, $\sum_{i=1}^{10}(x_i-\overline{x})^2=0^2+2^2+(-4)^2+(-2)^2+0^2+(-4)^2+(-1)^2+1^2+5^2+3^2\\\\\Rightarrow\ \sum_{i=1}^{10}(x_i-\overline{x})^2=76$

Then, $\sigma=\sqrt{\dfrac{76}{10}}=\sqrt{7.6}=2.76$

Hence, the standard deviation of his measurements = 2.76 g

6 0

2 years ago

Find the mean, median and mode of the weights of the people shown. 105kg 53kg 76kg 91kg 120kg 61kg 55kg 98kg 61kg

Yuliya22 [10]

First, you need to put them in order
53kg, 55kg, 61kg, 61kg, 76kg, 91kg, 98kg, 105kg, 120kg

For mean, you add them all up and divide by the amount of numbers (9)
720/9 = 80

For median, you find the middle number (76kg)

For mode, you find the number that appears the most (61kg)

Mean: 80
Median: 76
Mode: 61

5 0

1 year ago

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Imani is flying a drone. It takes off from a height of 24 feet above the ground and rises at a constant rate of 4.5 feet per sec

Firdavs [7]

Answer:

It will take 73 seconds.

6 0

1 year ago

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