Answer:
14418167
Step-by-step explanation:
The saddest part of this is that when I tried to do this by myself, I got a different answer, and then I looked it up all at once and I got 14418167.
The half life formula is :

where N(t) = remaining quantity after t years
No = Original Quantity
t = time in years
T = half life in years
From the problem, we have :
N(t) = 30 grams
No = 100 grams
T = 674
Solve for t :

Take ln of both sides :

The answer is t = 1170.71 years
Your answer is StartFraction 35 minus 21 Over 8 minus 4 EndFraction → 35–21/8–4
The probability that a student scored less than 55% on the exam is 0.134%.
<h3>What is a normal distribution?</h3>
It's the probability curve of a continuous distribution that's most likely symmetric around the mean. On the Z curve, at Z=0, the chance is 50-50. A bell-shaped curve is another name for it.
We have:
Mean of the sample = 70
Standard deviation = 5
= P(X<55%)
Z = (55-70)/5
Z = -3
P(X < -3)
From the Z table:
P(x<-3) = 0.0013499
or
P(x<-3) = 0.134%
Thus, the probability that a student scored less than 55% on the exam is 0.134%.
Learn more about the normal distribution here:
brainly.com/question/12421652
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