From the statement you can find the function that represents the percent of strontium-90 that remains after t years of the nuclear accident.
Call P the percent:
---> P = e ^ (- 0.025t)
Now you can also estimate the half-life of the isotope strontium-90:
Call Pi the initial percent and P2 the half percent:
P2 = 0.5 * P initial =>
P2 = 0.5 * Pinitial = Pinitial * e ^ (-0.025 t)
=> 0.5 = e ^ (-0.025t)
=> ln 0.5 = -0.025t
=> t = - ln (0.5) / 0.025
=> t = 27.7 years <----- half-time
9514 1404 393
Answer:
shaded/square = (50π cm²)/(400 cm²) = π/8
Step-by-step explanation:
The quarter circle has area ...
A = (1/4)(πr²) = π/4(20 cm)² = 100π cm²
The half-circle has area ...
A = (1/2)(πr²) = π/2(10 cm)² = 50π cm²
Then the area of the shaded portion is ...
shaded = 100π cm² -50π cm² = 50π cm²
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The area of the square is ...
A = s² = (20 cm)² = 400 cm²
Then the ratio of interest is ...
shaded/square = (50π cm²)/(400 cm²) = π/8
Answer:
The median is 9
Step-by-step explanation:
(2 - 5i) ( 2 + 5i) (i)
(4 + 10i -10i -25) (i)
(4 - 25) (i)
-21i
(2 - 3i) + (8 - 2i)
Get rid of all of the parenthesis.
2 - 3i + 8 - 2i
Combine like terms.
(-3i - 2i) + (2 + 8)
Simplify.
-5i + 10
~Hope I helped!~