3 years ago

15% is 75 of what number .NOT 75% is 15

Mathematics

1 answer:

Scorpion4ik [409]3 years ago

6 0

15 is 75 percent of the number 20 because 5 x 4 = 20 and 5 x 3 = 15. So look at 5 as 25% so multiply 5 x 3 to get 15

You might be interested in

The half-life of Radium-226 is 1590 years. If a sample contains 200 mg, how many mg will remain after 1000 years?

adell [148]

Answer: 129.33 g

Step-by-step explanation:

$$$Let $p=A \cdot e^{n t}$ \\$(p=$ present amount, $A=$ initial amount, $n=$ decay rate, $t=$ time)$

$\begin{aligned}&\Rightarrow \text { Given } p=\frac{A}{2} \ a t \ t=1590 \\&\Rightarrow \frac{1}{2}=e^{1590n} \Rightarrow n=\frac{\ln (1 / 2)}{1590}=-0.00043594162\end{aligned}$

$If $A=200 \mathrm{mg}$ and $t=1000$ then,$$\begin{aligned}P &=200 e^{\left(\frac{\ln \left(1/2\right)}{1590}\right) \cdot 1000} \text \\\\&=129.33 \text { grams}\end{aligned}$