Answer:
18 minutes
Step-by-step explanation:
A = A₀ (½)^(t / T)
where A is the final amount,
A₀ is the initial amount,
t is the time,
and T is the half life.
A = 140 when t = 10. Solve for the half life:
140 = 700 (½)^(10 / T)
0.2 = ½^(10 / T)
log 0.2 = (10 / T) log 0.5
10 / T = 2.32
T = 4.31
When A = 40, t is:
40 = 700 (½)^(t / 4.31)
0.057 = ½^(t / 4.31)
log 0.057 = (t / 4.31) log 0.5
t / 4.31 = 4.13
t = 17.8
Rounded to the nearest whole number, it takes 18 minutes.
Answer:
30
Explanation:
count from -5 all the way to 25
DESCENDING ORDER:-
25, 23, 5,0,-5,-19,-26,-31
Answer:
75 boys
Step-by-step explanation:
=
4x = 300
x = 75
The common ratio is 2, so the sum is
.. a1*(r^n -1)/(r -1)
.. = 4*(2^9 -1)/(2 -1)
.. = 4*511
.. = 2044
The sum of the sequence is 2044.