A bag contains 7 blue coins and 8 red coins a coin is removed at random and replaced by three other color

I think you didn't finish the question

given the radius of the cylindrical mold is 2 inches and height is 3 inches.

volume of the cylindrical mold = πr²h

= 3.14 × 2 × 2 × 3

= 37.68 in³

radius of the spherical mold is given = 2 inches

volume of the spherical mold = 4/3πr³

= 4/3 × 3.14 × 2 × 2 × 2

= 100.48/3 in³

difference between the amount of wax needed = 37.68/1 - 100.48/3

= ( 113.04 - 100.48 ) / 3

= 12.56/3

= 4.186...

so approximately 4.19 in³

hence, correct option is 4.19 in³

cheers!!!