For part (a) the answer is 400 grams for part (b) 198.63 grams and for part (c) 20 years.
<h3>What is exponential decay?</h3>
During exponential decay, a quantity falls slowly at first before rapidly decreasing. The exponential decay formula is used to calculate population decline and can also be used to calculate half-life.
We have an equation for radioactive decay:

a) Plug t = 0

m(0) = 400 grams
b) plug t = 20 years

After solving:
m(20) = 198.63 grams
c) Plug m(t) = m(0)/2 = 400/2 = 200 grams

x = 19.80 years ≈ 20 years
Thus, for part (a) the answer is 400 grams for part (b) 198.63 grams and for part (c) 20 years.
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No, the centroid and Circumcentre are not same but it is same in equilateral triangle.
The intersection of a triangle's perpendicular bisectors is called the circumcenter.A triangle's circumcenter is a location that is equally spaced from each of its vertices.The centroid of a triangle is the location where its medians connect.
Triangle's centroid is always within it. The centroid of a triangle is its center of gravity in physical terms. If the triangle is evenly distributed around the plane's surface and you want to balance it by supporting it at only one point, you must do it near the center of gravity.Are the circumcenter and centroid at the same location? In the case of an equilateral triangle, they will both be.
Therefore, the centroid and Circumcentre are not same but it is same in equilateral triangle.
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Hhhhmmmmm...
13.50 for food
2.40 for drink
Since there is a voucher for 1/3 of food,
13.50 multiplied by 1/3 is 4.5 which is the discount
13.50-4.5=9
9 is the final cost for the food.
Add 9 to 2.40 for the drink which results in a total of 11.40
To find the amount charged for service you multiply 11.40 by .15
11.40 × .15 = 1.71
You add 1.71 to 11.40
The total is 13.11