Answer: B.
Explanation:
Because I just took the test and got it right
The time it takes for 1g of strontium-90 to decay to 250 mg is; 57.6 years
<h3>What is the half life of an element?</h3>
The formula for half life is;
A(t) = A₀ * (¹/₂)^(t/t_1/2)
Where;
A(t) is amount left after t years
A₀ the initial quantity of the substance that will undergo decay;
t_1/2 is the half-life of the decaying quantity.
We are given;
t_1/2 = 28.8 years
A₀ = 1 g
A(t) = 250 mg = 0.25 g
Thus;
0.25 = 1 * (¹/₂)^(t/28.8)
log 0.25 = (t/28.8) log (1/2)
-0.60206 = (t/28.8) * -0.3010
t = 2 * 28.8
t = 57.6 years
Read more about half life at; brainly.com/question/11152793
Answer:
<h3>33.3%</h3>
Explanation:
profit percent = Sp-Cp/Cp * 100%
Sp is the selling price
Cp is the cost price
Let the selling price of the article be x
If it is sold with a profit of 25% of selling price, then;
Profit = 0.25x
Since Profit = Sp - Cp
0.25x = x - Cp
Cp = x - 0.25x
Cp = 0.75x
Substitute into the formula
Profit percent = 0.25x/0.75x * 100
Profit percent = 0.25/0.75 * 100
Profit percent = 1/3 * 100
Profit percent = 33.3%
Hence the profit percent is 33.3%
