Which biconditional is not a good definition?
a. an angle is a right angle if and only if its measure is 90°
b. an angle is acute if and only if its measure is less than 90°
c. two angles are congruent if and only if its measure are the same.
d. an angle is obtuse if and only if its measure is greater than 180°

The random variable x is the number of occurrences of an event over an interval of ten minutes. it can be assumed that the probability of an occurrence is the same in any two-time periods of an equal length. it is known that the mean number of occurrences in ten minutes is 5.3. the appropriate probability distribution for the random variable

The volume of a spherical hot air balloon v(r) = 4 3 ? r3 changes as its radius changes. the radius is a function of time given by r(t) = 3t. find the instantaneous rate of change of the volume with respect to t at t = 2.

Ashop has a sale that offers 20% off all prices. on the final day they reduce all the sale prices by 25% linz buys a ratio on the day. work out the overall percentage reduction on the price of the ratio