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# How to create your own problems

You can define a new problem and edit an existing problem on the "Edit problem" page:

- To
**create a new problem**, click on "Create new problem" on the assignment page of the assignment to which you want to add the new problem. - To
**edit an existing problem**, add the problem to one of your assignments, click on the problem title on the assignment page, then click on the "Edit" button in the top right corner.

**Warning:**
If you edit one of our built-in problems, a copy will be created automatically which will then become your own problem.
If you edit one of your own problems, __the changes will change that problem in all of your courses and assignments__.
If you want the changes to affect the current course only, please copy the problem first by clicking on the copy icon on the assignment page, and then edit the copy.

## Parts

- To
**add a new part**, click on one of the buttons at the bottom of the page: - "Add numerical part" adds a part where the solution is a number.
- "Add MC(1) part" adds a multiple choice part with radio buttons and exactly one correct solution.
- "Add MC(N) part" adds a multiple choice part with checkboxes and any number of correct solutions.
- To
**change the order of parts**, click on any blue area of a part and drag it up or down. The system will only let you change the order of parts if doing so does not result in an undefined variable in any part. Content is evaluated from top to bottom, and left to right within each line. - To
**delete a part**, click on the "x" in the top right corner of the part. The system will only let you delete a part if doing so does not result in an undefined variable in any other part.

## Variables

- You define a random variable by giving it a name on the left, e.g., "rate" and typing in
*rand(x, y)*on the right: it will then generate a random whole number between x and y (inclusive). For example,*rand(10,20)*gives you 10, 11, 12, ..., or 20. - You can modify the variable definition, e.g.,
*rand(10,20)/100*gives you 0.1, 0.11, 0.12, .. , or 0.2. - To add a new variable, click on the value (right) field of the last variable definition in the section.
- To save the new variable, click anywhere outside of the definition fields.
- To delete an existing variable, click on the "X" on the right. You can only delete a variable if it is not used anywhere in the problem.

## Title

You need to give each problem a title. No variables are allowed in the title.

## Intro, question and solution

- You can use variables and do calculations in the intro, questions and solutions.
- Enclose variables and mathematical expressions in curly brackets, e.g., {rate} or {rate*100}%.
- You can define new variables, e.g., {newrate = rate*2}.
- The last expression in curly brackets in the solution field is the solution, i.e., the answer the student has to provide, e.g., {newrate} or {PMT/newrate}.
- The following operators are supported within curly brackets: + - * / ^
- The following functions are supported within curly brackets. Each function requires a function name, an opening parenthesis, one or more function arguments (separated by commas), and a closing parenthesis, e.g., {min(0, rate)}. If you require additional functions, please contact us at instructors@accepi.com.
- Basic 1-argument functions: sqrt, abs, ln, log, round, floor, ceil
- Probabilistic 1-argument functions: N (standard normal cumulative distribution function)
- Trigonometric 1-argument functions: sin, sinh, arcsin, asin, arcsinh, asinh, cos, cosh, arccos, acos, arccosh, acosh, tan, tanh, arctan, atan, arctanh, atanh
- 2-argument functions: min, max
- Financial functions (enter the interest rate as a decimal; set "type" to 0 for ordinary annuities and 1 for annuities due)
- fv(rate, nper, pmt, pv, type) (see Excel's FV function)
- ipmt(rate, per, nper, pv, fv, type) (see Excel's IPMT function)
- irr(cash flow 1, cash flow 2, cash flow 3, ...) (see Excel's IRR function)
- nper(rate, pmt, pv, fv, type) (see Excel's NPER function)
- npv(rate, cash flow 1, cash flow 2, cash flow 3, ...) (this function does not discount the first cash flow, unlike Excel's incorrect NPV function)
- pmt(rate, nper, pv, fv, type) (see Excel's PMT function)
- ppmt(rate, per, nper, pv, fv, type) (see Excel's PPMT function)
- pv(rate, nper, pmt, fv, type) (see Excel's PV function)
- rate(periods, pmt, pv, fv, type) (see Excel's rate function)

- If you want to use more advanced symbols, such as ratios or summation signs, you can use
**Ascii math**: - You need to enclose the expression in backticks, e.g., `{rate}/5` and `sum_(i=1)^\infty x_i` will display as `0.12/5` and `sum_(i=1)^\infty x_i`.
- Use _ for subscript and ^ for superscript.
- Enclose regular text in double quotation marks to keep it as regular text.
- For more syntax information please visit http://asciimath.org/
- You cannot have any formatting within the backticks, e.g., sub/superscript in the font (only with _ and ^) or bolded text.
- Since the final solution for each part is always bolded, the last set of curly brackets (the solution) cannot be enclosed by backticks.

## Multiple choice parts

- For MC parts, you need to fill out the question field, but the explanation field is optional.
- You need to fill out at least one answer. There is no limit on the number of possible answers.
- You cannot define new variables in the answer text.
- For MC(1) parts, you need to click on one of the radio buttons to designate the correct answer.
- For MC(N) parts, you can check any number of checkboxes to designate the correct answer. Students will only get points for the part if they check all correct answers and none of the incorrect answers.

More questions? Please contact us at instructors@accepi.com.