Answer: 2 kanban card sets will be needed.
Explanation: 20% of 10 gauges gives the safety inventory stock.
This will be 20/100 ×10=2
But 10 gauges are produced per hour out of which 2 will be kept as safety inventory stock, making it to be 10-2=8gauges per hour.
Number of kanban cards used for transporting gauges 8/5=1.6
1.6= 2to the nearest whole number.