the following data is given:

t = 10,   20,    30,    40     

R= 30,  15,   7.5,  3.75

 

Which of the following numbers best describes the halving time (half-life)? (To answer the question you may draw a semi-log plot, i.e., plot logR

log⁡R against t, but may also be able to guess it by looking at the data.)

 

a) 5

b) 20

c) -10

d) 10