The half life of Sodium-24 is 15 hours. If we have 10 grams of Sodium-24, how much will remain after 15 hours?​

Did you ever figure out the right answers since you asked?

The boat's velocity relative to the riverbank can be resolved into two components. the component going north is 2.7 m/s and the component going west is 1.2 m/s.we add these two vectors and then find the magnitude of the resultant to get the speed.the magnitude of the resultant vector from adding can be obtained by the pythagorean theorem.    to two significant figures, the boat's speed relative to the riverbank is 3.0 m/s.