First find the difference (1,200,000 - 750,000) which is 450,000. so how long does it take to fill 450,000 cm3? what i did was do 50% of 750,000 which is 375,000 then do 10% of 750,000 which conviniently comes up to 450,000 when added together so it takes 60% of 30 minutes to fill the remaining diffrence. 50% of 30 is 15 and 10% is 3 so 15+3 = 18 minutes. so to fill the pool you do, time of 750,000 + time of 450,000 = time of 1,200,000 (30 + 18 = 48)
Step 1: Find out how many cm3 is filled in a minute. 750000/30 = 25000cm3 per minute Step 2: Find out how many minutes it takes to fill 1200000cm3. 1200000/25000 = 48 minutes
