--- id: 6350805fe0fe283dd347b0dc title: Step 10 challengeType: 0 dashedName: step-10 --- # --description-- The mean is the average value of all numbers in a list. The first step in calculating the mean is to take the sum of all numbers in the list. Arrays have another method, called `.reduce()`, which is perfect for this situation. The `.reduce()` method takes an array and applies a callback function to condense the array into a single value. Declare a `sum` variable and assign `array.reduce()` to it. # --hints-- Your `getMean` function should have a `sum` variable. ```js assert.match(getMean.toString(), /sum/); ``` Your `getMean` function should use the `.reduce()` method of the `array` parameter. ```js assert.match(getMean.toString(), /array\.reduce\(\s*\)/); ``` You should assign the result of `array.reduce()` to the `sum` variable. ```js assert.match(getMean.toString(), /sum\s*=\s*array\.reduce\(\s*\)/); ``` # --seed-- ## --seed-contents-- ```html Statistics Calculator

Statistics Calculator

Enter a list of comma-separated numbers.

The mean of a list of numbers is the average, calculated by taking the sum of all numbers and dividing that by the count of numbers.

Mean:

The median of a list of numbers is the number that appears in the middle of the list, when sorted from least to greatest.

Median:

The mode of a list of numbers is the number that appears most often in the list.

Mode:

The range of a list of numbers is the difference between the largest and smallest numbers in the list.

Range:

The variance of a list of numbers measures how far the values are from the mean, on average.

Variance:

The standard deviation of a list of numbers is the square root of the variance.

Standard Deviation:

``` ```css body { margin: 0; background-color: rgb(27, 27, 50); text-align: center; color: #fff; } button { cursor: pointer; background-color: rgb(59, 59, 79); border: 3px solid white; color: white; } input { background-color: rgb(10, 10, 35); color: white; border: 1px solid rgb(59, 59, 79); } .bold { font-weight: bold; } ``` ```js --fcc-editable-region-- const getMean = (array) => { } --fcc-editable-region-- const calculate = () => { const value = document.querySelector("#numbers").value; const array = value.split(/,\s*/g); const numbers = array.map(el => Number(el)).filter(el => !isNaN(el)); } ```