A sample contains 60% of its original amount of Fermium-257. The half-life of Fermium-257 is about 100 days. About how old is th
e sample? 52 days 60 days 74 days 136 days
1 answer:
Answer:
74 days
Step-by-step explanation:
The proportion left after d days is ...
p = (1/2)^(d/100)
When that proportion is 60%, we have ...
.60 = .50^(d/100)
log(.60) = (d/100)log(.50) . . . . . take logarithms
100·log(.60)/log(.50) = d ≈ 73.697 ≈ 74 . . . days
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Boys to Girls = 2:7
Boys = x
Girls = 250+x
Setup the ratio
x:(250+x) = 2:7
x / (250+x) = 2/7
7x = 500+2x
7x-2x = 500
x = 500/5 =100
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It would be 8 and a half hours.
Answer:
segment XY = 6
segment XW = 5
segment WZ = 4
segment ZY = 5
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Answer:
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Step-by-step explanation:
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