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Filename: controllers/calculator.php

Line Number: 37

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A normal curve can to converted to standard normal curve by the formula

Z = X – mean/ Std deviation

Percentages of the area of the curve with standard deviation 1, 2 and 3 is given by

-1<= Z <= 1 68.27%

-2<= Z <= 2 95.45%

-3 >= Z <= 3 99.73%

Any positive value of z is found in z-table.

In this case we consider the full right hand side area = 0.5. Then subtract the area between 0 and 1.06 using the z table.

P(Z>1.06) = 0.5 – P(0

0.5 – 0.355 = 0.1446

We will do the following

P(0 < Z < 4.00) = P(0< Z < 1.06)

= 0.5 – 0.3554

= 0.1446.