In order to calculate the z-score of a normal distribution, you need to apply the formula:
z = (o - m) / s
where:
o = observed value
m = mean
s = standard deviation
In your case:
z = (259 - 239) / 25 = 0.8
The answer is, indeed, z = 0.8
45=1,3,5,9,15,45
37=only 1 and 37 because it is prime.
51= 1,3,17,51
Answer:
Step-by-step explanation:
Statement Reason
1. ∠4 is an exterior angle of ΔABC Given
2. ∠3 and ∠4 form a linear pair Linear pair property
3. ∠3 is supplementary to ∠4 Straight line property
4. m∠3+m∠4=180° ∠3 is supplementary to ∠4
5. m∠1+m∠2+m∠3=180° Triangle sum theorem
6.m∠1+m∠2+m∠3= m∠3+m∠4 Statement 4 and 5
7. m∠1+m∠2=m∠4 Subtraction property
Answer:

Where
represent the half life and the intial amount would be 
And we want to find the time in order to have a 95% of decay so we can set up the following equation:

If we apply natural log on both sides we got:

And solving for t we got:

So then would takes about 14.26 hours in order to have 95% of the lead to decay
Step-by-step explanation:
For this case we can define the variable of interest amount of Pb209 and for the half life would be given:

Where
represent the half life and the intial amount would be 
And we want to find the time in order to have a 95% of decay so we can set up the following equation:

If we apply natural log on both sides we got:

And solving for t we got:

So then would takes about 14.26 hours in order to have 95% of the lead to decay