To calculate what is asked we use the formula for radioactive decay. It is expressed as follows:
An = Ao (e^(-kt))
We calculate as follows:
An = Ao (e^(-kt))
74 = 100 (e^(-k(10)))
k = 0.0301
1/2 = (e^(-0.0301t))
t = 23 hours
Hope this answers the question.
Most fool-proof way to do this in my opinion is to simply expand everything and write it out, i.e.

Throwing this into a calculator, we get
23.032To the nearest cent, this gives us
$23.03
I think it is the first option. hope this helps :)
Explicación paso a paso:
La distancia recorrida el primer día = 500 m
Si aumenta la distancia en 200 m diariamente, entonces el total corrido diariamente formará una progresión aritmética con el último término de 10 km (10,000) como se muestra;
500, (500 + 200), (500 + 200 + 200) ... 10,000
500, 700, 900 ... 10,000
para que sepamos el número total de días usados para la carrera, usaremos la fórmula para calcular el enésimo término de una secuencia aritmética como se muestra;
where;
n es el número de términos
a es el primer término de la secuencia
d es la diferencia común
Dado a partir de la secuencia:
a = 500
Tn = 10,000
d = 700-500 = 900-700 = 200
Sustituir en la fórmula y calcular el valor de n

Andrea habría alcanzado los 10.000km tras 48,5 días de carrera
Answer:
3 2/3 square feet.
Step-by-step explanation:
You just need to multiply 6 and 4 2/3. To do this you have to change both of them into improper fractions so 6 would be 21/3 and 4 2/3 would be 14/3. If you cross cancel the 21/3 will become 7/3 and the 14/3 will become 14/1. Now you have to multiply across and you should get 98/3. To change the improper fraction into a mixed number you have to divide 98 and 3 so you can get 3 2/3. Therefore, the answer to the area of the quilt is 3 2/3 square feet.