70(0.21) + 99(0.23) + 91(0.23) + 90(0.33)
= 14.7 + 22.77 + 20.93 + 29.7
= 88.1%
Answer:
2
Step-by-step explanation:
14 times 5= 70
10 times 7= 70
70 is the LCM for 14 and 10, least common multiple meaning the least difference, then subtract to get 2
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Answer: 2/3
Explanation: the difference between -14 and -10 is 4 and in fractions x/y. so we have 4/y. the difference between -18 and -12 is 6 so we have 4/6 but we can simplify that to 2/3.
The answer to this question is B. 105
<span>As the age of the U-235 sample is 2.631 billion years, and the half-life of U-235 is 713 million years, the sample has undergone 2.361 X 1,000,000,000 / 713 X 1,000,000 = 3.69 half lives. In each half-life the sample reduces to half its original weight according to the radioactive Half-Life Formula:
ln (Nt /N0) = -kt, where N0 = mass of the original weight of radioactive material, Nt = mass of radioactive material at time t, k = decay constant and t = time interval . We have to put Nt/N0 = 1/2 for time interval = half-life.</span>