What is the standard form of the number in the calculators display?

2.3e-9
a: 0.23
b: 0.23
c: 2,300,000,000
d: 23,000,000,000

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3. be sure to show that you know the formula and how to plug into it. also, clearly state the margin of error.

Sundar used linear combination to solve the system of equations shown. he did so by multiplying the first equation by 5 and the second equation by another number to eliminate the y-terms. what number did sundar multiply the second equation by? 2x+9y=41 3x+5y=36

20 ! brainliest ! add and simplify your answer.