I need help with 9 and 10

Asample of a population should be large enough to: a. justify the cost of the items needed for the simulation. o b. include more than half of the entire population. o c. span the full spectrum of a population's genetic variation, o d. generate a very large amount of data.

Which of the following would have the highest terminal fall velocity? silt topsoil clay small pebbles

Janice has just measured the destiny of an object which value is possible (knowing that density =m/v)