A book has 12 chapters about flying birds, 5 chapters about flying insects, 4 chapters about land insects, and 4 chapters about land mammals. If the probability of picking a chapter about certain types of animals is $\frac{8}{25}$, what type of animal is the chapter about?

The period of a pendulum is equal to $2 \pi \sqrt{\frac{l}{g}}$, where l is the length of the pendulum and g is the acceleration due to gravity. If the length of the pendulum is 40 m and the acceleration due to gravity is $10 \mathrm{~m} / \mathrm{s}^2$, what is the period of the pendulum?

To build Ariane's house will take a constant number of individual work days. If a construction crew of 15 people can build the house in 20 days, how many people does it take to finish the house in 5 days?

How many years did the Dust Bowl last?

The equation y = 4 describes a horizontal line with zero slope. The equation x = 4 describes a vertical line with infinite slope. Classify the system formed by these two equations.

Solve the inequality $\frac{n}{5} \leq-3$. Then select several values of $n$ to substitute into the inequality to verify the answer.

Use the values from the table to draw a scatter plot.

True or False: The lines represented by $y=\frac{x}{4}-2$ and 4y = x + 8 are parallel. Explain.

How have political and ethnic struggles shaped the Eastern Europe of today?

Maria has a white gold ring with a mass of 10.3 grams and a volume of 0.7 cubic centimeters. White gold is made of nickel and gold. Nickel's mass is 9 grams per cubic centimeter and gold's mass is 19 grams per cubic centimeter. What is the volume of each metal in the ring?

Verify that $3 g h \sqrt{275 g^7 h^9}$ can be simplified to $15 g^4 h^5 \sqrt{11 g h}$.

Write an equation for a direct variation that includes the point (13,13).

The speed of a pitched ball is represented by the expression $9 x^2-36 x-13$. Factor the expression completely.

In an antique shop, a painting is inclined on a display easel at an angle of 65 degrees. The angle of inclination can be increased or decreased by a maximum of 8 degrees from the present setting by an adjustment screw. Write and solve an absolute-value equation for the maximum and minimum angles of inclination for the easel.