Question

Fluorine-18 is a radioactive isotope of fluorine that is used in medical imaging scans. It has a

half-life of approximately 110 minutes. If a patient has a medical imaging scan using an

injection of fluorine-18 at 9 am, at what time will there be less than 25% of the radioactive

isotope in her body?

a) 10 am

b) 12 pm

c) 1 pm

d) 11 am​

Answer 1

Answer:

Let the present age of Nuri  =x year

And present age of Sonu =y year

Five years ago

Age of Nuri =x–5years

Age of Sony =y–5years

Nuri was thrice as old as Sonu

X−5=3(y–5)

X–5=35–15

X–3y=−15+5

X–3y=−10                       ………..(1)

Ten years later,

Age of Nuri  =x+10

Age of Sonu =y+10

Nuri will be twice as old as Sonu.

X+10=2(y+10)

X+10=2y+20

X–2y=10                           ………..(2)

X–3y=−10                        ………..(1)

Subtracting equation (1) from equation (2)  we get

Y=20

Plug this value in equation first we get

X−3∗20=−10

X=60–10

X=50

Hence age  of Nuri =50 years and age of Sonu =20 years

Answer 2

Answer:

I think 12 pm answer questions