Answer of the following code should be OK, I guess?

Question

https://code.sololearn.com/cIFaNws4r5n2/?ref=app

Answer 1

Everything's down to precision.
A double type number is more precise than a float type number. So, a float and a double can't be same because the precision of both are different (both have different interpretations for the same decimal number).

Answer 2

Because the variable "a" defined as a floating-point number stores the number 0.100000001

Answer 3

That's because 0.1 must be clearly defined as a float. So 0.1f