Hi all, cloud you help me on this form.

I want, based on selected value to calculate, make an other cost (days * 20) and placed into the nCost.

Really thank you for your time in advance.

Code:
<HTML>
<Head>
<Script type="text/javascript">
var radioCollection, checkedButton;
var frm = document.forms["Cost"];
if(frm){
    radioCollection = frm.elements["nEmp"];
    if(radioCollection){
        /* The collection of like-named radio buttons has a length
           property and that is used to limit a for loop:-
        */
        for(var c = 0;c < radioCollection.length;c++){
            /* The individual radio buttons are accessed as indexed
               members of the collection using the loop counter - c
               - from the for loop:
            */
            if(radioCollection[c].checked){
                /* When a radio button element is found with its
                   checked property set to boolean true a reference
                   to that element is assigned to the local variable
                   - checkedButton - and the loop is terminated with
                   the - break - statement as only one button in a set
                   of like-named radio buttons will be checked at a
                   time, so any remaining buttons in the collection
                   must have checked properties set to false:
                */
                checkedButton = radioCollection[c];
                break;
            }
        }
        if(checkedButton){
            /* I want, based on selected value to calculate, make an other cost (days * 20) and placed into the nCost.
            */
			function calcCost(nForm){
			var cost = 0;
			var n = nform.nEmp.value;
			if (n <=200){cost = 4*20}
			else if (n > 200 && n < 226){cost = 2*20}
			else if (n > 225 && n < 426){cost = 4*20}
			else 	{cost = n*25}
			nForm.nCost.value = cost+".00";
        }
    }
}

	}
</Script>
</Head>
<Body>
<Form name='Cost'>
<fieldset id="options">
<legend>Please select </legend>
<ol>
<li><input type="radio" name="nEmp" id="option1" value="225"/><label for="option1">option1 = 2 Days</label> </li>
<li><input type="radio" name="nEmp" id="option2" value="200"/><label for="option2">option2 = 4 Days</label> </li>
<li><input type="radio" name="nEmp" id="option3" value="425"/><label for="option3">options3 = 6 Days</label> </li>
</ol>
</fieldset>    
Cost: $<input type='text' name='nCost' size='8' readonly>
<br><br>
<input type='button' value='Calculate' onclick="calcCost(this.form)">
</Form>
</Body>
</HTML>