The percentage of eighth-graders that chose History as their favorite subject is 19%
<h3>Percentages and proportion</h3>
From the given table, we have the following parameters
Total students in the 8th grade = 124 students
Total number of 8th graders that chose history = 11 + 12
Total number of 8th graders that chose history = 23
Required percentage = 23/124 * 100
Required percentage = 19%
Hence the percentage of eighth-graders that chose History as their favorite subject is 19%
Learn more on percentages here: brainly.com/question/24304697
If
is the amount of strontium-90 present in the area in year
, and it decays at a rate of 2.5% per year, then

Let
be the starting amount immediately after the nuclear reactor explodes. Then

or simply

So that after 50 years, the amount of strontium-90 that remains is approximately

or about 28% of the original amount.
We can confirm this another way; recall the exponential decay formula,

where
is measured in years. We're told that 2.5% of the starting amount
decays after 1 year, so that

Then after 50 years, we have

This area is equal to the sum of a circle with a radius of 5/2 in and a rectangle 5 by 15 in so:
A=πr^2+xy
A=π(2.5)^2+5*15
A=6.25π+75 in^2
A≈94.63 in^2 (to nearest hundredth) so
A≈95 in^2 (to nearest whole square inch)
Answer:
Z=1
Step-by-step explanation: