Answer:
30
Step-by-step explanation:
First, find out how many half-lives have passed. Divide the number of minutes by the length of a half-life.
20÷10=2
2 half-lives have passed.
Now figure out how much nitrogen will be left after 2 half-lives have passed. Multiply the starting amount of nitrogen by
1/2
a total of 2 times.
120x1/2 1/2=30
That calculation could also be written with exponents:
120x(1/2)2=30
After 2 half-lives, the amount of nitrogen left will be 30 grams.
The above question has to do with proportionality, specifically direct proportionality.
Direct proportionality means when an item x is directly proportional to an item y. This is represented mathematically as:
x ∝ y
90 cookies will serve 45 students.
The number of cookies needed for 30 students is 90 cookies
From the above question,
45 cookies will serve 15 students
Hence,
15 students = 45 cookies
30 students = ?
Cross Multiply
30 students x 45 cookies / 15 students
= 90 cookies.
Therefore, 90 cookies will serve 45 students.
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Answer:
83.33%
Step-by-step explanation:
The 3 goes on and on