Randomisation and Try another question like this one

gistfile1.txt

The following generates crudely a coprime pair of numbers. However on choosing Try another question like this on you get the same output pair very time


{
	notes: ""
	name: MAS3214 20122013 CBA3_1
	percentPass: 50
	shuffleQuestions: false

	rulesets: {
		std:[all,fractionNumbers, !collectNumbers,!noLeadingMinus]
	}
			
	navigation: {
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	feedback: {
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	questions: [
		{
			name: MAS3214 20122013 CBA3_1

			variables: {
				b: "random(100..200)"
				a: "random(100..200)"
				r:"chcopair(a,b,a,b)"

			}
								
			functions: {
				chcopair: {
					parameters: [[a,number],[b,number],[m,number],[n,number]]
					type: list
					definition: "if(gcd(m,n)=1,[m,n],chcopair(a,b,random(a..b),random(a..b)))"
			
				}
		
			}

			parts: [
				{
					type: gapfill

					prompt: """
						{r}
					"""
					
					gaps: [
						
					]
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			advice: """
				
			"""
		}
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}