How would you prepare 500 mL of 5% dextrose added to water from a 50% stock solution?

Question

_________ mL 50% dextrose + ________mL water

Answer 1

You are reducing the concentration by a factor of 10, so you need to increase the volume by a factor of 10.
So, 50mL of 50%, filled to a volume of 500mL means you need to add 450mL of water.