the weight of the substance after 28 years is 8 grams.
<h3>How to determine the amount</h3>
We have that the half life of a substance is defined as the time required for the substance to decrease by half
The formula for calculating the half - life of a material is given as;
Where
- N(t) is final amount
- No is the initial amount = 128 grams
- t1/2 is the half life = 7 years
- t is the time elapsed = 28 years
Substitute into the formula
N(t) = 128 × (0. 5) ^28/ 7
N (t) = 128 × ( 0. 5) ^ 4
N(t) = 128 × 0. 0625
N(t) = 8 grams
Thus, the weight of the substance after 28 years is 8 grams.
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Answer:
25%
Step-by-step explanation:
The number of people who went to the local swimming pool in the;
first week = 1120
second week ( 105 fewer people) = 1120 - 105 = 1015
third week (135 more people) = 1015 + 135 = 1150
fourth week (310 fewer people|) = 1150 - 310 = 840
The percent decrease in the number of people who went to the pool over these four weeks
= (1120 - 840)/1120 * 100%
= 280/1120 * 100%
= 1/4 * 100%
= 25%
It means that the number of people who went to the local swimming pool over the 4 weeks decreased by 25%
Answer:
y =x² + y² + 2y - 35
Step-by-step explanation:
The equation of a circle is given by the formula;
(x-a)²+(x-b)² = r²
Where; (a, b) is the center of the circle and r is the radius
Therefore;
(x-0)² +(y+1) = 6²
x²+ y² +2y + 1= 36
x² + y² + 2y - 35 = 0
Therefore; The equation of the circle is y = x² + y² + 2y - 35
Answer:
<h2>18</h2>
Step-by-step explanation:
The formula of a distance between two points:
We have the points (5, -7) and (5, 11). Substitute:
