The question can be solved using conservation of linear momentum.
= 0.06kg and
= 0.03kg
Let the initial velocity of Marble A be ,
= 0.7m/s
Let the initial velocity of Marble B be,
= 0m/s
Let the velocity of Marble A after collisiong ,
= -0,02m/s
Let the velocity of Marble B after collision be 
From the conservation of linear momentum equation. We get,

Substituting the values we get,
(0.06)(0.7) + 0 = (0.06)(-0.02) + (0.03)
we get,
= 1.44m/s
Answer: 1479watts
Explanation:
Power is defined as the energy expended or work done in a specific time.
Mathematically,
Power = Workdone/time taken
Since work done is force × distance
Power = force × distance/time
Force = Mary's weight = 87N
Distance = height of the flight = 102meters
Time = 6.0seconds
Substituting in the formula we have;
Power = 87 × 102/6
Power = 1,479watts
Note that the time must be in seconds before usage. If its given in minutes, you will have to convert to seconds
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