# 4.9. Exercises: Data and Variables¶

Exercises appear regularly in the book. Just like the concept checks, these exercises will check your understanding of the topics in this chapter. They also provide good practice for the new skills.

We've included our solutions to some (but not all) of the exercises so that you can check your own work after you practice. As with any learning opportunity, take it seriously and give every exercise a fair shot before peeking at the solution. Our solution may not look exactly like yours, but that's ok. There's often more than one way to solve a problem with code.

You don't need to show proof of completing the exercises to pass, so do them for your own benefit. And if they're hard or you get some answers wrong on the first try, keep going! Your future self will thank you.

Unlike the concept checks, you will need a code editor to complete the exercises. Fortunately, you created a free account on Repl.it as part of the prep work.

Use this Repl.it link to get started solving.

## 4.9.1. The Data¶

Use the information given below about your space shuttle to complete the exercises:

Data

Value

Name of the space shuttle

Determination

Shuttle Speed (mph)

17,500

Distance to Mars (km)

225,000,000

Distance to the Moon (km)

384,400

Miles per kilometer

0.621

## 4.9.2. The Exercises¶

1. Declare and assign variables

Declare and assign a variable for each item in the list above.

Hint: When declaring and assigning your variables, remember that you will need to use that variable throughout the rest of the exercises. Make sure that you are using the correct data type!

2. Print out the type of each variable

For each variable you declared in part A, use the `typeof` operator to print its type to the console, one item per line.

Click "Run" (in repl.it) and verify that your code works before moving to part C.

3. Calculate a space mission!

We need to determine how many days it will take to reach Mars.

1. Create and assign a miles to Mars variable. You can get the miles to Mars by multiplying the distance to Mars in kilometers by the miles per kilometer.

2. Next, we need a variable to hold the hours it would take to get to Mars. To get the hours, you need to divide the miles to Mars by the shuttle's speed.

3. Finally, declare a variable and assign it the value of days to Mars. In order to get the days it will take to reach Mars, you need to divide the hours it will take to reach Mars by 24.

Using variables from above, print to the screen a sentence that says `"_____ will take ___ days to reach Mars."` Fill in the blanks with the shuttle name and the calculated time.
Repeat the calculations, but this time determine the number of days it would take to travel to the Moon and print to the screen a sentence that says `"_____ will take ___ days to reach the Moon."`.