The purpose of blocking in experimental design is: a. to give the quarterback enough time to throw the ball. b. to control for multiple variables in an experiment. c. to prevent response bias from entering into the experiment. d. to keep the subjects from knowing if they are in the treatment group. e. to keep the experimenter from knowing which subjects are in the treatment group.

In statistics, blocking refers to the arrange of experimental units in groups, where each subject have a specific characteristic in common, for example the gender.

So, by dividing the sample into blocks, where each block is almost independent one to another, it helps to manage studies with multiple variables, which it can imply a higher difficulty when the research have to analyse results, because they need to demonstrate or reject a specific relation between variables, if there are too many, it's better to divide the sample in to specific groups, classified depending on their particular characteristics which make them independent, that is, one group doesn't affects other groups.

Using this method in the experimental design, researches are assuring the reliability of the results. Therefore, the correct option is B: blocking has the purpose of controlling multiple variables in an experiment.

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.