After 5 days, you have half left.
After 10 days, that's half of the half again = a quarter.
After 15 days, that's half of a quarter = an eighth.
After 20 days, that's half an eighth = one sixteenth.
After 25 days = 1/32
After 30 days = 1/64
After 35 days = 1/128
After 40 days = 1/256
After 45 days = 1/512
After 50 days = 1/1024th of the initial radiation.
110 days would be 11 half-life periods if the half-life is 10 days. That means at the end, 1/2 x 1/2 x 1/2 ... (11 times) would be left: 2-11, or about one part in two thousand.
This would be 1/210 or 1/1024 radiation left
C.1/32
The half life is the time it takes for half the atoms in a given sample to decompose. Knowing this then after 27 days there is half the amount left. After 54 days then there is half that half left so that's a quarter.
200
If I take a radioactive sample of 400 moles of an unknown substance and let it decay to the point of three half-lives I would have 50 moles left of the sample. 1/2 of what is left will decay in the next half-life. At the end of that half-life I will have 25 moles left of the unknown substance or 4/25.
In a reactor, or atomic bomb, uranium 235 (for example) will not always split into the same kinds of atoms; rather, different kinds of waste products can be produced. Some of them will decay faster, some slower. The real problem is with products that have a half-life of a few decades or centuries. If a product (like uranium itself) has a half-life of billions of years, the radiation it gives off will not be very significant. If on the other hand a product has a half-life of days - well, the radiation will be very strong, but after a few weeks not much is left. However, part of the nuclear waste can remain for decades or centuries, and still give off a significant amount of radiation. No specific timeframe can be given - if (say) a certain isotope has a half-life of 50 years, that means that after 50 years, half of the substance will be left; after another 50 years, a quarter of the original substance, etc. It will not suddenly disappear at a certain moment; but after several times the half-life, the amount left will be insignificant. On the other hand, the by-products of this decay can again be other radioactive isotopes.
With radioactive decay, predicting when any individual atom will decay is nearly impossible. However, when a lot a particles are present, then it is possible to get a general idea of how much will decay in a certain period of time. The half-life is this measurement, and it is the time that it takes for one halfof the substance to decay. Hence half-life or how long it takes for half to "die".For any size sample of a substance, the half-life is how long it takes for half to be left, so for a substance with a half-life of 2 days, half of the substance will decay in two days. Therefore your answer is simply half of 30g which is 15g.Additional reading: http://simple.wikipedia.org/wiki/Radioactive_decay
Assuming that "half" refers to "half-life", 360/60 = 6 so fraction left = 1/26 = 1/64
54 days is 2x27. After one cycle of a half life (27 days), one-half of the substance would be left. After a second cycle of a half life (27 more days, for a total of 54), one-half of one-half is left, or one-fourth.
1/4 of the cake is left.
The half life is the time it takes for half the atoms in a given sample to decompose. Knowing this then after 27 days there is half the amount left. After 54 days then there is half that half left so that's a quarter.
Eight days would be four half-lives. One-half to the fourth power is one-sixteenth. So you would have half a gram left.
1/4. After 27 days, half of the material will have decayed. After another 27 days half of the remaining material will have decayed. Half of half is 1/4.
3/8
1/3
1/3 pizza left.
Left Fraction was created in 1940.
A non-unit fraction is a fraction that has something other than a 1 in the numerator.
One eighth would be left.