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# What is the symbol used here (on the left of -1.86)?

### 4 Answers

- PuzzlingLv 72 months agoFavorite Answer
In a mathematical context, I believe this is related to the standard normal curve. The phi symbol (Φ) represents the proportion of data to the left of a z-score of -1.86.

As you should know, the standard normal curve is a "bell curve" with a mean of 0 and a standard deviation of 1.

When you are asking for Φ(-1.86) you are looking for the proportion (or percentage) of values that are more than 1.86 standard deviations below the mean.

Because the curve is symmetric and the total proportion is 1, we could equivalently figure out the area to the left of 1.86 and subtract it from 1.

Φ(-1.86) = 1 - Φ(1.86)

Using a calculator, or a standard normal lookup table, you can find out the value of Φ(1.86) is 0.9686.

Subtracting from 1, we get that there is about 0.0314 of the data that is to the left of -1.86. That's 3.14%.

Look at the picture below to see that about 3.14% of the data is in the shaded area.

- JimLv 72 months ago
Phi (Φ φ), is Greek alphabet. The letter Phi is used to represent the golden ratio (which is about 1.618).

It looks here like they meant it to be like 𝑓(x) as a function symbol.

Also:

It can also be used as the nth cyclotomic polynomial, for any positive integer n, is the unique irreducible polynomial with integer coefficients that is a divisor of x n − 1 x^{n}-1 and is not a divisor of x k − 1 x^{k}-1 for any k < n. Its roots are all nth primitive roots of unity e 2 i π k n } e^{2i\pi , where k runs over the positive integers not greater than n and coprime to n (and i is the imaginary unit).