When two dice are rolled, find the probability of getting: (as reduced fractions)

a) A sum of 5 or 6
b) A sum greater than 9
c) A sum less than 4 or greater than 9
d) A sum that is divisible by 4
e) A sum of 14
f) A sum less than 13

large crystals result from very slow cooling.

evaporation of water: this would produce an evaporite which is a sedimentary rock. like a salt pan in a desert. not possible to have volcanic rocks originate this way.

crystalization in molten earth: slow cooling over time. (hundreds to millions of years)

crystalization at earth's surface: this results in fast cooling. (a few hours to a few months or years)

crystalization from cooling off hot water: that would be a hydrothermal deposit. while associated with volcanics they are not volcanic rocks themselves and usually occur fairly rapidly.