question 11 (1 point)\nalexas gross monthly pay is $3810.\nto maintain her current way of life, how much…

question 11 (1 point)\nalexas gross monthly pay is $3810.\nto maintain her current way of life, how much should she have saved by the time she retires?\n$457,200\n$464,400\n$487,200\n$493,600\nquestion 12 (1 point)\nradon - 219 has a half - life of about 4 s.\nafter 20 s, how many milligrams of a 500 mg sample will remain?\n435.3 mg\n211.6 mg\n31.3 mg\n15.6 mg

question 11 (1 point)\nalexas gross monthly pay is $3810.\nto maintain her current way of life, how much should she have saved by the time she retires?\n$457,200\n$464,400\n$487,200\n$493,600\nquestion 12 (1 point)\nradon - 219 has a half - life of about 4 s.\nafter 20 s, how many milligrams of a 500 mg sample will remain?\n435.3 mg\n211.6 mg\n31.3 mg\n15.6 mg

Answer

Answer:

Question 11: $457,200 Question 12: 15.6 mg

Explanation:

Question 11

Step1: Use retirement - savings rule

A common rule is to have 120 times your monthly income saved for retirement.

Step2: Calculate savings amount

$3810\times120 = 457200$

Question 12

Step1: Calculate number of half - lives

The number of half - lives $n=\frac{20}{4}=5$.

Step2: Use half - life formula

The formula for the remaining amount $A = A_0\times(\frac{1}{2})^n$, where $A_0 = 500$ mg and $n = 5$. So $A=500\times(\frac{1}{2})^5=500\times\frac{1}{32}=15.625\approx15.6$ mg.