What volume of 98% sulphuric acid should be mixed with water to obtain 200mL of 15% solution of?

Get a ruler in your hands. Measure things until you start to understand how a ruler works. Measure some stuff and figure out where the center is. Say you measure a book and it's 7/8" thick. You look at your ruler and see that every eighth is divided into two sixteenths, so obviously half of 7/8" is going to be 7/16". If you write that out you have 1/2 x 7/8 = 7/16. And you notice that 1/2 is divided into 2/4 and then into 4/8 and so on, so you can convert anything to anything by multiplying all the numbers on top and then all the numbers on bottom.

Other rulers are divided into 10 and 100 parts. But an inch is still an inch, so anything on one ruler can be translated to the other ruler. A half inch on one ruler is 5/10 or 50/100 on the other. An eighth inch is just 12.5 marks when you have 100 marks per inch. A metric ruler divides an inch into 25.4 parts, so a half inch would be 12.7 of those parts. Pretty simple, isn't it? Practice this a bit and people will think you went to wizard school.

Percent is simply a ruler with 100 marks. The only confusion is trying to keep track of what the marks represent, since that changes from time to time.

200ml x 1.12g/ml x 0.15 = 33.6 g acid. Now you need the amount of 98% solution that has that amount.

sulphuric acid(98%)=1.88g/cm3

33.6g/(1.88g/cm) = 17.87234cm You do it that way because you need g both above and below the fraction line so they will cancel.

So now you have 17.87234 ml (I hope you know ml = cm^3) and you want 200 ml, so you just get some water and fill it up.

200 - 17.87234 = 182.12766 ml <-- ANSWER

As per my opinion we need to mix approximately 289.1 mL of 98% sulphuric acid with water to obtain 200ml of 15% solution.

I hope my answer helps you to understand about sulphuric acid.