I don't understand how this works..

Can someone help me understand the following?

**I can do it all, but I don't understand how M(z,cat) equals 0.79**?

The Site Wind Speed, Vz, is all the five wind factors multiplied together

Vz = V * Mls* M(z,cat) * Mt * Mr (m/s)

The information for M(z,cat) is :

Terrain

Category 3

Building Height (m) 7.5

(z,cat) 0.79

The numbers pertaining to the above are taken from a table, I will recreate here :

Multiplier, M

(z,cat)

Height, z Terrain Category 3

(m)

≤3 0.75

5 0.75

10 0.83

15 0.89

I really don't get the relationship between 0.75, Category 3 and 0.79 are,

I don't understand what I need to do to have the answer equal 0.79?!

Can someone help me please?!

Thanks,

WTF