The total mass of a box and 3 similar tennis balls = 1.02 kilograms.
when the number of tennis balls in the box is tripled the mass becomes = 2.16 kg.
Let’s find the mass of the empty box.
=> there are 3 balls, then it was tripled
=> 3 * 3 = 9
a total of 9 balls
=> 2.16 kg – 1.02 kg
=> 1.14 let’s divide this with 6 tennis balls
=> 0.19 (weight of each tennis balls)
=> 0.19 * 3 = 0.57
=> 1.02 – 0.57 = 0.45, the weight of an empty box.