An native american tepee is a conical tent. find the number of cubic feet of air in a teepee 10 ft. in diameter and 12 ft. high. 100 cu. ft. 300 cu. ft. 400 cu. ft.

For this case what you should know is that by definition the volume of the cone is given by:
 V = ((pi) * (r ^ 2) * (h)) / (3)
 Remembering that:
 r = d / 2
 Substituting the values:
 V = ((pi) * ((d / 2) ^ 2) * (h)) / (3)
 V = ((pi) * (((10) / 2) ^ 2) * (12)) / (3)
 V = 314.16 ft ^ 3
 
 V = 314.16 ft ^ 3
 The nearest option is:
 300 cu. ft