RunningAverage Class on playground (updated)

you have 10 RA objects of size 60 and 5 RA objects of size 24, that is a lot of memory (at least for an UNO)

Every object has 10 bytes local vars and 4 bytes per element.

15 objects = 150 bytes
10 x 60 x 4 = 2400 bytes
5 x 24 x 4 = 480 bytes

roughly 3000+ bytes of SRAM

What board are you using?
If it is an UNO, it does not have that much memory, ==> Get a MEGA.

Learning point for me: The RA class has no error handling or state to see its "health".
Analysis:
The class does not check if the allocation of the needed "arrays" succeed, but the code behaves as if it does so.
That means that only the first RA object are healthy and the others have internal pointers pointing to (probably) NULL.

To make it more robust the interface of the Class could change to have a method

bool begin(uint8_t size) ;

that returns true is size elements could be allocated.
The allocation should be removed from the constructor.
// this is a breaking interface change

Another alternative is to have a method
uint8_t internalSize();
That returns the size of the internal size. This returns zero if allocation had failed and the internal size otherwise.
// this would not break the existing interface and would increase footprint not much.