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Filename: controllers/formulas.php

Line Number: 37

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confidence interval is calculated after setting the confidence level. The confidence level in percentage,

mostly set at 95%. Which means 95% of the values will fall within the range for a specific outcome. The

confidence interval formula is given as

When n greater than or equal to 30 then confidence interval = x +-z

But when n is less than 30 then the formula is confidence interval = x +-t

a = 1 - (confidence level/ 100)

What will be the confidence level at 95% level?

N= 30, x = 20, std deviation = 10, level = 0.95 and a = 1 – (95/100) = 0.05

Plug in the values into the formula

Confidence interval = 20 +-t

20 +- 2.09302 (10/5.477) = 20 +- 3.821 = 16.178 to 23.821

deviation is 5. What will be the confidence level at 95% level?

N= 25, x = 10, std deviation = 5, level = 0.95 and a = 1 – (95/100) = 0.05

Plug in the values into the formula

Confidence interval = 10 +-t

10 +- 2.09302 (5/5)

10 +- 3.821 = 6.178 to 13.821