Median is a middle value
So it is 28
2 trikes (6 wheels) and 47 bikes (94 wheels)
or
4 trikes (12 wheels) and 44 bikes (88 wheels)
or
6 trikes (18 wheels) and 41 bikes (82 wheels)
or
8 trikes (24 wheels) and 38 bikes (76 wheels)
or
10 trikes (30 wheels) and 35 bikes (70 wheels)
As long as you start our with an even number of trikes, you'll find a way to use up all the tires with no remainders.
To find the surface area of the figure , we need to add the surface area of all the faces
So the surface area of figure = Area of two lateral rectangular faces + Area of two triangular faces + area of base
hence
Surface Area of figure = 2(10*15) + 2( 1/2 * 8 * 12) + (12*15)
= 300 + 96 + 180
= 576 square feet
So correct option is the last one