Answer: 68
Step-by-step explanation:
Formula for sample size when prior estimate of population proportion (p) is available: 
, where z*= critical-value.
E= Margin of error.
Let p be the population proportion of trees are infected with the citrus red mite.
As per given , we have

E= ± 0.08
The critical z-value corresponding to 90% confidence level = z*=1.645
Substitute all the values in the above formula , we get
Required sample size :

[Rounded to next integer.]
Thus, the minimum sample size should be taken =68
The answer is 45.65
45 + 6.5 = 45.065
45 divided by 6.5 over a hundred = 45 + 0.065
Thats how you get 45.65
Answer:
70, 140, 280, 350
Step-by-step explanation:
Obviously, it must have the factors 2, 5, 7 as a minimum, so the smallest value is 2×5×7 = 70.
Any of these primes can be added to the product. In increasing order, the smallest additional factors will be 2, 4, 5, 7, 8, 10, ...
So, the four smallest numbers with prime factors of 2, 5, and 7 are ...
70 = 2·5·7
140 = 2²·5·7
280 = 2³·5·7
350 = 2·5²·7
900=(1/2)*b*10*15
1800=150b
b=12
I hope you can figure out FC with this info.