How to get the result of random item with different possibility? [duplicate]

Question

I'm wondering if anyone can guide me with following problem... Each fruit has different chance to be called out.

Apple - 80% 
Orange - 10%
Banana - 10%

Each time a user click on the random image, only 1 fruit will come out with above weight. I have no idea how I can calcuate to get that result. Pseudo code example is fine for me.

Answer 1

Randomize a number between 1 and 100, then:

n <= 80: show Apple
n > 80 and n <= 90: show Orange
n > 90 and n <= 100: show Banana

Answer 2

int TotalWeight = 100;
int[] ItemWeights = new int[] {80, 10, 10};
enum Items {Apple, Orange, Banana}


Items GetRandomItem()
{
    int random = Random.Next(TotalWeight);
    int i=0;  

    while (random > ItemWeights[i])
    {
        random -= ItemWeights[i];
        i++;
    }

    return (Items) i;
 }