Answer:
35
Step-by-step explanation:
Here we see 5 black keys for every 7 white keys.
So the ratio is 5:7
If we need 49 white keys, find the amount we scale the original ratio by:
49/7 = 7
So we are scaling by a factor of 7.
The number of black keys would be 5 * the scale of 7. = 35
So there should be 35 black keys.
Answer:

Step-by-step explanation:
Taking into account that the growth rate of the number of species on the island is proportional to the density of species (number of species between area of the island), a model based on a differential equation is proposed:

This differential equation can be solved by the method of separable variables like this:
with what you get:

. Taking exponentials on both sides of the equation:


how do you have to
, then

Multiply each side by 9:
18 + 4x > 36 + 9x
Subtract 18 from each side:
4x > 18 + 9x
Subtract 9x from each side:
-5x > 18
Divide each side by -5:
x < -3.6
Hope this helps!
Answer:
Check the explanation
Step-by-step explanation:
Open file in excel.
Click on Data->Data Analysis and select Regression.
Enter wait time data range in y-variable.
Enter Duration data range in x-variable.
Click ok.
From above output:
#1 The equation of the linear regression line is:
A 95% confidence interval for the slope of the regression line is:

In excel, ise formula =FORECAST(6,wait time data range, duration data range) and press enter. The wait time between eruptions following a 6 minute eruption is 
Since (for F test)
, we can conclude that there is a statistically significant linear relationship between the duration of the eruptions and the wait time between eruptions.
The correct null and alternative hypotheses for this analysis:

Kindly check the output below