Dilution Math PLEASE help! I can't figure this out!?

Question

What is the percentage strength of a solution that is made by adding 200 ml of purified water to 600 ml of a 25% solution?

My answer is 75%, but my workbook answer states it is 18.75%. I have no idea how that answer was achieved. Help! Thank you!

Answer 1

You have 600 ml of a 25% solution. That solution thus has 450 ml of water and 150 ml of whatever. You add 200 ml of water. You now have 800 ml of solution, 150 ml of which is not water.

150 / 800 = 18.75 %

Answer 2

Getting a pole on a bus. For his thirteenth birthday, Adam grew to become into allowed to holiday right down to Sarah ’ s carrying products keep to purchase a clean fishing pole. With super exhilaration and anticipation, Adam boarded the bus on his very own and arrived at Sarah ’ s keep. even if the determination of fishing poles grew to become into large, there grew to become into purely one pole for Adam and he bought it: a 5 - foot, one - piece fiberglass “ Trout Troller 570 ” fishing pole. while Adam’s return bus arrived, the driving force reported that Adam ought to no longer board the bus with the fishing pole. gadgets longer than 4 feet weren't allowed on the bus. Adam remained on the bus cease protecting his captivating 5 - foot Trout Troller. Sarah, who had observed the entire ordeal, rushed out and reported, “ We ’ ll get your fi shing pole on the bus! ” optimistic sufficient, while the comparable bus and the comparable driving force decrease back, Adam boarded the bus along with his fi shing pole, and the driving force welcomed him aboard with a grin. How grew to become into Sarah waiting to have Adam board the bus along with his 5 - foot fi shing pole without breaking or bending the bus - line regulations or the pole?