Staals half
1 gram left
0.3 grams left
half lives are normally written in years
it goes likt this
A=final amount
P=initila amount
t=time elapsed
h=time half life is (same units as time)
let's use days as the units of time
we are given
initial amount=1gram
final amount=0.3gram
time=4 days
so
solve for h
take the ln of both sides
times both sides by h
divide both sides by ln(0.3)
use calculator
h=2.30287
3 sig figs
h=2.303 days
Answer:
a. 0.38%
b. 266.75 days
Step-by-step explanation:
We have the following data, mean (m) 269 and standard deviation (sd) 15, therefore:
a. The first thing is to calculate the number z:
z (x) = (x - m) / sd
z (309) = (309-269) / 15 = 2.67
When looking in the normal distribution table (attached), we have that at this value of z, the probability is:
P (z> 2.67), that is to say we must look in the table -2.67 and this value corresponds to 0.0038, that is to say 0.38%
b. Find the z-value with a left tail of 44%, i.e. 0.44. We look in the table for this value and what value of z corresponds.
invNorm (0.44) = -0.15
Find the corresponding number of days:
x = z * sd + m
we replace
d = -0.15 * 15 + 269 = 266.75 days
One number is 4
Another is 2 I hope this helped
<span>The numbers are 4 and 7
j^2+k^2=65
4^2+7^2=65
16+49=65
65=65
hope i helped</span>
Answer:
x
=
13
+
6
=
19
Step-by-step explanation:
this is so simple