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3 years ago

a biologist wants to determine the effect of a new fertilizer on tomato plants. what would be the control

2 answers:

6 0

The control could be sunlight, water, temperature, or the type of soil, but i would have to go with a main one, the type of plant, tomato plant. hope i helped.

leonid [27]3 years ago

3 0

First, the biologist must define the variables:

Dependent- this is what will be measured. So the biologist may want to measure the weight and height of the tomatoes, or the leaf area or the time it will produce the fruit.

Independent- this is what will differ in the experiment and what the biologist thinks will affect the dependent variable. In this case, the biologist will use new fertilizer on plant A, old fertilizer on plant B, and no fertilizer on plant C.
Controlled- these variables must be held constant because the biologist doesn’t want other factors to affect the growth of the tomato plant, thus, destroying the purpose of the experiment, tomato plant A, B, and C will have equal amounts of soil, water, and carbon dioxide, and exposure to sunlight.

After his experimentation, he will conclude which of the plant has better weight, growth, leaf, and fruit. If Plant A is the best tomato plant of them all, then he can say that the new fertilizer is more effective.

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In Sarah‘s dance class 1/16 of the girls are also on the soccer team. what is the decimal form of this fraction

Alenkasestr [34]

Answer:0.0625

Step-by-step explanation:

5 0

4 years ago

Penny and Kenny have the same number of football cards.

Pachacha [2.7K]

Hello,
Penny==>a*10 (a is an integer)
Kenny==>b*18 (b is an integer)

a*10=b*18==>a=9*b/5 ==>b=5+n*5
a=9*(5+5*n)/5=9*(1+n)=9+9n
If n=0 then a=9 and b=5 :Number od cards: 9*10=10, 5*18=90
if n=1 then a=19 and b=10: Number of cards: 19*10=190>100 to exclude.

So number of cards=90

7 0

3 years ago

a certain number of two digit is three times the sum of its digit and if 45 added to it the digit will be reversed find the numb

bogdanovich [222]

· Author has 184 answers and 67.6K answer views
Let the number be (10 x + y)

Then, 10 x + y = 3 * (x + y) (given)

Or, 10 x + y = 3 x + 3 y

Or, 10 x - 3 x = 3 y - y

Or, 7x = 2 y

Or, x = 2 y / 7 ( Eq. 1)

Also, 10 x + y + 45 = 10 y + x ( given)

Or, 10 x - x = 10 y - y - 45

Or, 9 x = 9 y - 45 ( Eq. 2)

Substituting the value of x from (Eq. 1) in (Eq. 2), we have:

9 * 2 y / 7 = 9 y - 45

Or, (9 y ) - (18 y / 7) = 45

Or, 63 y - 18 y = 315

Or, 45 y = 315

Or, y = 7

From (Eq. 1),

x = 2 * 7 / 7 = 2

So, the number is 10 x + y = (10 * 2) + 7 = (20 + 7) = 27

Answer

Check:

Sum of the digits = 2 + 7 = 9

9 * 3 = 27 ✓

Adding 45 to the number 27, we get 72. So, the digits get reversed.

5 0

3 years ago

Find 62(9) . Express your answer as a fraction in simplest form

Bas_tet [7]

Answer:

558/1

Step-by-step explanation:

7 0

3 years ago

Read 2 more answers

In a study of 420,095 Danish cell phone users, 135 subjects developed cancer of the brain or nervous system (based on data from

Maksim231197 [3]

Answer:

$z=\frac{0.0003214 -0.00034}{\sqrt{\frac{0.00034(1-0.00034)}{420095}}}=-0.654$

$p_v =2*P(Z$

So the p value obtained was a very high value and using the significance level given $\alpha=0.005$ we have $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can say that the true proportion not differs significantly from the specified value of 0.00034 or 0.034%.

Step-by-step explanation:

1) Data given and notation

n=420095 represent the random sample taken

X=135 represent the subjects developed cancer of the brain or nervous system (based on data from the Journal of the National Cancer Institute as reported in USA Today)

$\hat p=\frac{135}{420095}=0.0003214$ estimated proportion of subjects developed cancer of the brain or nervous system (based on data from the Journal of the National Cancer Institute as reported in USA Today)

$p_o=0.00034$ is the value that we want to test

$\alpha=0.005$ represent the significance level

Confidence=99.5% or 0.995

z would represent the statistic (variable of interest)

$p_v$ represent the p value (variable of interest)

2) Concepts and formulas to use

We need to conduct a hypothesis in order to test the claim that the brain or nervous system at a rate that is different from the rate of 0.0340% :

Null hypothesis: $p=0.00034$

Alternative hypothesis: $p \neq 0.00034$

When we conduct a proportion test we need to use the z statistic, and the is given by:

$z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}}$ (1)

The One-Sample Proportion Test is used to assess whether a population proportion $\hat p$ is significantly different from a hypothesized value $p_o$ .

3) Calculate the statistic

Since we have all the info requires we can replace in formula (1) like this:

$z=\frac{0.0003214 -0.00034}{\sqrt{\frac{0.00034(1-0.00034)}{420095}}}=-0.654$

4) Statistical decision

It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.

The significance level provided $\alpha=0.005$ . The next step would be calculate the p value for this test.

Since is a bilateral test the p value would be:

$p_v =2*P(Z$

4 0

3 years ago