Asample of phosphorus-32 has a half-life of 14.28 days. if 55 g of this radioisotope remain (1 point) unchanged after approximately 57 days, what was the mass of the original sample? 

it is called kinetic energy

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles