How many times is it necessary to increase the potential energy of elastic deformation of the rubber band of a child’s slingshot

How many times is it necessary to increase the potential energy of elastic deformation of the rubber band of a child’s slingshot so that when a pebble is shot vertically upward, its maximum lifting height increases by a factor of n = 4? Disregard air resistance.

Given:
E1 is the potential energy of an elastically deformed child’s slingshot;
h1 – the height reached by a pebble released from a children’s slingshot;
h2 = 4 * h1 – the height should increase by 4 times.
It is required to determine E2 / E1 – how many times it is necessary to increase the potential energy of an elastically deformed children’s slingshot so that the condition h2 = 4 * h1 is met.
Since, according to the condition of the problem, the shot is fired vertically upward, and the air resistance can be neglected, then according to the law of conservation of energy, the potential energy of elastic deformation of the slingshot at the maximum height is converted into the potential energy of a pebble, that is:
E1 = Ep = m * g * h1, where m is the mass of the pebble.
Similarly for the second case:
E2 = m * g * h2. Then:
E2 / E1 = m * g * h2 / (m * g * h1) = h2 / h1 = 4 * h1 / h1 = 4 times.
Answer: the potential energy of elastic deformation of the slingshot also needs to be increased by 4 times.