Answer:
The correct answer would be = t = 2.112 billion years
Explanation:
Given:
The number of crystal of uranium = 275 billion
The number of crystal of lead = 1925 billion
The half-life for 235U = 704 million years
Formula using :
N = N0e−λt
where,
no. of daughter atoms = N
at time t= 0, No. of parent atoms = N0.
Time = T
Half life = 0.693/λ
Decay constant = λ
Solution:
by putting value in the formula of the half-life
λ = 0.693/0.704
λ = 0.9844
Now, putting value in the formula for the age of granite.
275 = (275+1925)e^-0.9844 t
1/8= e^-0.9844 t
e^0.9844 t = 8
taking log
0.9844t = 2.07944
t = 2.112 billion years
