Answer:
B
Step-by-step explanation:
Answer: x=4
Step-by-step explanation:
We know that line segment AC= AB + BC
we also know that AB= 3x+8 and BC= 2x-5
by substituting these, we get AC= (3x+8)+(2x-5)
AC is given as being 23, so we know that
23= (3x+8)+(2x-5)
by combining like terms, we get that
5x+3=23
simplify this to get that x=4
Answer:
im gussing sorry if its wrong :(
Step-by-step explanation:
1=a
2=d
3=b
4=c
Write an equation system based on the problem
"Agatha is five times older than her son, Bob" could be written as:
a = 5b.......(first equation)
"Three years ago, she was nine times older" could be written as:
a - 3 = 9(b - 3)......(second equation)
Solve the equation system
To find the value of b, substitute 5b as a to the second equation
a - 3 = 9(b - 3)
5b - 3 = 9(b - 3)
5b - 3 = 9b - 27
5b - 9b = -27 + 3
-4b = -24
b = -24/-4
b = 6
Her son, Bob, is 6 years old
To find Agatha's age, substitute the value of b to the first equation
a = 5b
a = 5 × 6
a = 30
Agatha is 30 years old
Answer: 16590
Step-by-step explanation:
The formula we use to find the sample size is given by :-
, where p = prior estimate of population proportion.
= Critical z-value (Two- tailed)
E= Margin of error .
Let p be the population proportion of cyanobacteria.
Given : E = 0.01
Critical value for 99% confidence interval : 
If Ian does not want to rely on previous knowledge , then we assume p=0.5 because the largest standard error is at p=0.5.
Now, the required sample size = 
Required sample size = 16590
