Answer:
The dilution is 1/4.
Explanation:
Dilution is the process of decreasing the concentration of any substance by adding the diluent into it. If we want to prepare 1:5 dilution of bacterial culture in 10 ml than 2 ml of bacterial culture should be added in 8 ml of diluent making total solution 10 ml.
So the dilution comes 1:5 after dividing 2 ml bacterial suspension with 10 ml of total solution(2/10=1:5). Therefore similarly addition of 75ml of diluent in 25 ml bacterial culture makes total 100 ml and in that 100 ml, 25 ml is bacterial suspension.
So by dividing 25 ml bacterial suspension by 100 ml of total solution we will get 1/4 ratio. Therefore the correct answer is 1/4.
