The half life

The half-life of a radioactive isotope is the time it takes for a quantity of the isotope to be reduced to half its initial mass. Starting with 145 grams of a radioactive isotope, how much will be left after 3 half-lives?

Result

m3 =  18.125 g

Solution:

m0=145 g  m3=m0 0.53=145 0.53=1458=18.125 gm_{0}=145 \ \text{g} \ \\ \ \\ m_{3}=m_{0} \cdot \ 0.5^3=145 \cdot \ 0.5^3=\dfrac{ 145 }{ 8 }=18.125 \ \text{g}



Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!





Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...):

Showing 0 comments:
1st comment
Be the first to comment!
avatar




Tips to related online calculators
Do you want to convert time units like minutes to seconds?

Next similar math problems:

  1. One half
    one_half One half of ? is: ?
  2. Five harvests
    zrno In the seed company, they know that, out of 100 grains of a new variety, they get an average of 2000 grains after harvest. Approximately how many grains do they get out of 100 grains after five harvests?
  3. Population
    population_2 What is the population of the city with 3% annual growth, if in 10 years the city will have 60,000 residents?
  4. Compound interest 3
    exp_growth2 After 8 years, what is the total amount of a compound interest investment of $25,000 at 3% interest, compounded quarterly? (interest is now dream - in the year 2019)
  5. The crime
    crime The crime rate of a certain city is increasing by exactly 7% each year. If there were 600 crimes in the year 1990 and the crime rate remains constant each year, determine the approximate number of crimes in the year 2025.
  6. Family
    4kids Family has 4 children. Ondra is 3 years older than Matthew and Karlos 5 years older than the youngest Jane. We know that they are together 30 years and 3 years ago they were together 19 years. Determine how old the children are.
  7. Geometric progression 2
    exp_x There is geometric sequence with a1=5.7 and quotient q=-2.5. Calculate a17.
  8. Six terms
    sequence_geo_3 Find the first six terms of the sequence a1 = -3, an = 2 * an-1
  9. Five members
    pst3.JPG Write first 5 members geometric sequence and determine whether it is increasing or decreasing: a1 = 3 q = -2
  10. Geometric sequence 4
    Koch_Snowflake_Triangles It is given geometric sequence a3 = 7 and a12 = 3. Calculate s23 (= sum of the first 23 members of the sequence).
  11. Tenth member
    10 Calculate the tenth member of geometric sequence when given: a1=1/2 and q=2
  12. GP - 8 items
    fn Determine the first eight members of a geometric progression if a9=512, q=2
  13. Theorem prove
    thales_1 We want to prove the sentence: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started?
  14. The city
    city_1 At the end of 2010 the city had 248000 residents. The population increased by 2.5% each year. What is the population at the end of 2013?
  15. The city 2
    kingkong Today lives 167000 citizens in city. How many citizens can we expect in 11 years if their annual increase is 1%?
  16. Quotient
    fun1_1 Determine the quotient and the second member of the geometric progression where a3=10, a1+a2=-1,6 a1-a2=2,4.
  17. Powers
    1power Express the expression ? as the n-th power of the base 10.