Half life can be used to solve for the amount (A) of a substance left after t time by using the following equation: A = Ao .(1/2) ^ t/h
If the half life of a substance is 4 weeks, how long will it take for 400 mg of this substance to decay to 25 mg?
Select one:
O A 16 weeks
O B. 6 weeks
O C. 8 weeks
O D. 13 weeks

where is the figure

a: 1/6, j: 1/4

step-by-step explanation: you are welcome

25 questions , because they start with 100.  

350-100=250 .  

. 250/10=25

step-by-step explanation:

first take off 100, then what x 10 = 250? that is your answer. (25)

d. 24+-0.114

step-by-step explanation:

the question requires us to calculate the approximate 95% confidence interval for the mean number of ounces of ketchup per bottle in the sample given the following statistics;

sample mean = 24

standard deviation, σ = 0.4

sample size , n = 49

the confidence interval for a population mean is calculated using the formula;

sample mean ± z-score*(σ/sqrt(n))

the z-score associated with a 95% confidence interval, from the standard normal tables, is;

1.96

substituting these values into the formula;

24 ± 1.96*(0.4/7)

= 24 ± 0.112

from the alternatives given, choice d is closest to the above expression;