Billiard table all six pockets), with rounded entrances and nearly parallel sides, like those on a snooker table. One tactical consequence of this design difference is that the jaws of the WPA-type pocket are often used exactly like a horizontal version of the backboard of a basketball goal, to rebound the ball into the pocket; this technique does not work on blackball tables, and even shots down the cushion into a corner pocket are more difficult. For tournament competition under WPA world-standardized rules (and league play under derived rulesets), the bed of the pocket billiard table must be made of slate no
Standard normal table σ, the standard error is σ/√"n": Z tables are typically composed as follows: Example: To find 0.69, one would look down the rows to find 0.6 and then across the columns to 0.09 which would yield a probability of 0.25490 for a "cumulative from mean" table or 0.75490 from a "cumulative" table. Because the normal distribution curve is symmetrical, probabilities for only positive values of Z are typically given. The user has to use a complementary operation on the absolute value of Z, as in the example below. Z tables use at least three different conventions: This table gives a