Question

Write an If-Then statement that displays the message "The number is not valid" if the variable speed is outside the range 0 through 200 .

Short answer

Question: Write an If-Then statement that displays a specific message if a variable called "speed" is outside the range of 0 through 200. Answer: ``` If (speed < 0) OR (speed > 200) Then Display "The number is not valid" End If ```

Step-by-step solution

Write the condition to check if the speed is outside the range 0 through 200

To check if a number is outside a given range, we need two conditions; one is to check if the number is smaller than the lower bound, and the other is to check if the number is greater than the upper bound. In this case, the lower bound is 0, and the upper bound is 200. We can express this condition using the logical OR operator to connect the two conditions. Condition: (speed < 0) OR (speed > 200)

Construct an If-Then statement with the condition

Now that we have the condition to check whether the speed is outside the given range, we can create an If-Then statement using this condition. If the condition is true, i.e., the speed is outside the range, we will display the message "The number is not valid." If-Then statement: ``` If (speed < 0) OR (speed > 200) Then Display "The number is not valid" End If ``` The final solution is the If-Then statement above, which checks if the variable "speed" is outside the range 0 through 200 and displays the desired message if it is.

Key concepts

Conditional Logic

Conditional logic deals with "if-then" statements that allow programs to make decisions and execute specific code based on whether certain conditions are met. In the exercise provided, we want to determine if the variable "speed" is outside the allowable range of 0 to 200. To accomplish this, we structure a conditional statement that evaluates whether certain criteria are true.

• The "if" part specifies the condition to be checked. In this case, it consists of two checks: whether "speed" is less than 0 or greater than 200.
• The "then" part dictates what action to take if the condition is met. Here, the action is to display the message "The number is not valid."

The beauty of conditional logic lies in its simplicity, enabling dynamic responses by evaluating true or false statements. Understanding how to construct and apply these statements is crucial, as it forms the backbone of decision-making in programming.

Logical Operators

Logical operators, such as AND, OR, and NOT, are essential tools in building complex conditional statements. These operators are used to join multiple conditions and evaluate them in combination. For this particular problem, we use the OR operator, which checks if at least one of the provided conditions is true.

• OR Operator: Used when at least one of two conditions needs to be satisfied. In our case, the speed being either less than 0 or greater than 200 will trigger the action.


• AND Operator: This requires both conditions to be true, which isn't needed for this exercise but is useful when all conditions must be satisfied before proceeding.


• NOT Operator: Reverses the truth value of a condition, allowing flexibility in handling exceptions.

In the context of our exercise, the OR operator effectively evaluates if the speed is outside the specified range, ensuring that the program runs correctly and responds appropriately whenever any of these primary conditions is met.

Programming Basics

Understanding programming basics involves learning core concepts such as variables, control flow, and the syntax of the language you are using. Our exercise requires familiarity with concepts like variables and control structures, which are fundamental in writing executable programs.

• Variables: Think of these as containers that store data values. In this exercise, "speed" is a variable containing the speed we want to evaluate.


• Control Structures: These dictate the order in which statements and instructions are executed. The If-Then construct is a primary control structure that allows for specific code execution based on set conditions.


• Syntax: This refers to the set of rules that define the combinations of symbols that are considered as a correctly structured program in a given language. Keeping syntax accurate in If-Then statements ensures that the program interprets instructions correctly and functions as expected.

As you dive deeper into programming, grasping these basics will empower you to handle more complex problems, gradually building a comprehensive understanding of how programs work and how they can be used to solve real-world challenges.