In a certain population, the two most heavily diagnosed diseases are schistosomiasis and malaria. over the past five years, malaria has accounted for more than half of all disease cases, and schistosomiasis, which accounted for 40% of all disease cases in the community five years ago, accounted for 30% in the past year.

According to the above statement, the conclusion is that if the total number of Schistosomiasis cases are increased over the past five years, then the total number of cases of this disease must have increased by more than 30%. Because five years ago the percentage of cases are 40% and the number of cases are 40/100, so the last year the number of cases of disease are 60. Total increase = 60/30 x 100 = 200, it means total cases which are increases 100% which is more than 30%.