I know the answer, because of calculators, but I can't quite figure out how to do it without one and I just want an explanation on how the answer was made. Please help :)

There are 40 volunteers for the research study on the Power Pill. Each subgroup of the study will contain 10 participants. Determine how many ways these participants can be selected and explain your method.

The answer correct answer is 847660528.

Muscles, a membership-only gym is hoping to open a new branch in a small city in pennsylvania that currently has no fitness centers. according to their research approximately 12,600 residents live within driving distance of the gym. muscles sends out surveys to a sample of 300 randomly selected residents in this area (all of who respond) and finds that 40 residents say they would visit a gym if one was located in their area. based on the past survey research, muscles estimates that approximately 30% of these respondents would actually join the gym if they opened one in the area. based on this information and the results of the sample survey, about how many residents should muscles expect to join its new branch? a) 134 b) 504 c) 1,680 d) 3,780

The weight of an object in the water is 7% of its weight out of the water. what is the weight of a 652g object in the water?

The table below shows the approximate height of an object x seconds after the object was dropped. the function h(x)= -16x^2 +100 models the data in the table. for which value of x would this model make it the least sense to use? a. -2.75 b. 0.25 c. 1.75 d. 2.25