A tumor is injected with 0.1 grams of lodine-125, which has a decay rate of 1.15% per day. To the nearest day, how long will it take for half of the lodine-125 to decay?
days

hi,  

1 - 0.015 = 0.985

so we have :  0.1 *0.985 ^n = 0.05

                              0.985^n =  0.05 /0.1

                              0.985^n = 0.5

                                        n =  ln (0.5) /ln (0.985)

                                         n ≈ 46

Let's check :   0.1*0.985^46 ≈0.0498

b

step-by-step explanation:

7. d. 64

8. i. 32

9. c. 125

10. j. none of the above

11. d. 81

12. i. 216

13. e. none of the above

14. g. 240

15. e. none of the above

16. g. 32

17.   e. none of the above