Answer:
31.25
Step-by-step explanation:
The half life is 5.3 years
This means that 1.2 of the orginal matter is left after every 5.3 years.
To find this, divide 26.5(total years) by 5.3(hald life)
This gets you 5.
This is how many times half life occurs, or how many times the total mass is split in half.
This can be though of 1/2^5th power
Or
1/32
Now, lets mutliply this by the 1000 total mass:
1000*1/32
=
31.25g
This is your answer!
Hope this helps!