Lua add chance to random items

[zirra]

So I don't wanna try adding a bunch of codes hoping it works, I've searched for this and came up empty already. I want to add chance to certain items. like a 1% chance for one item and the rest equally random. I know this is probably something easy but I can't think of which way to do it. For ex; Item 11640 needs to have a much rarer probability. near impossible. while the others are all random with equal chance.

local items = {{2152, 10}, {2394, 100}, {2391, 37}, {2392, 4}, {11640, 1}, {11641, 1}}
local min_level = 20    --Minimum level to pick up the items in the chest.
local time = 1440     --how many minutes to recive reward.
local storage = 91838
function onUse(cid, item, frompos, item2, topos)
    if getPlayerLevel(cid) >= min_level then
        if getPlayerStorageValue(cid, storage) < os.time() then
            local it = items[math.random(#items)]
            doPlayerAddItem(cid, it[1], it[2])
            doPlayerSendTextMessage(cid, 27, "You have received "..it[2].." "..getItemNameById(it[1])..". You can take your reward in "..time.." minutes.")
            setPlayerStorageValue(cid, storage, os.time() + time * 60)
        else
            return doPlayerSendCancel(cid, "You have already received your reward for today.")
        end
    else
        return doPlayerSendCancel(cid, "You do not have the required level to receive this reward ["..min_lv.."].")
    end
    return true
end

 

[Mkalo]

local items = {{2152, 10}, {2394, 100}, {2391, 37}, {2392, 4}, {11641, 1}}
local rareitems = {{11640, 1}} -- {itemid, count}
local rarechance = 1/100 -- 1 out of 100, 1%
local min_level = 20    --Minimum level to pick up the items in the chest.
local time = 1440     --how many minutes to recive reward.
local storage = 91838
function onUse(cid, item, frompos, item2, topos)
    if getPlayerLevel(cid) >= min_level then
        if getPlayerStorageValue(cid, storage) < os.time() then
            local rd = math.random(1, 100)
            if rd <= rarechance*100 then
                local it = rareitems[math.random(#rareitems)]
                doPlayerAddItem(cid, it[1], it[2])
                doPlayerSendTextMessage(cid, 27, "You have received "..it[2].." "..getItemNameById(it[1])..". You can take your reward in "..time.." minutes.")
                setPlayerStorageValue(cid, storage, os.time() + time * 60)
            else
                local it = items[math.random(#items)]
                doPlayerAddItem(cid, it[1], it[2])
                doPlayerSendTextMessage(cid, 27, "You have received "..it[2].." "..getItemNameById(it[1])..". You can take your reward in "..time.." minutes.")
                setPlayerStorageValue(cid, storage, os.time() + time * 60)
            end
        else
            return doPlayerSendCancel(cid, "You have already received your reward for today.")
        end
    else
        return doPlayerSendCancel(cid, "You do not have the required level to receive this reward ["..min_lv.."].")
    end
    return true
end

This will have 1% chance to give a random item from rareitems

 

[zirra]

omg, haha thank you so much @MatheusMkalo.