First use compound interest formula
P(1+ r/100)^n
P stands for principal which is amount of monry invested
r stands for the rate in terms of percentage
n stands for the no. of years. But in this case, its months so u need to do one extra step which
5/12
hence cmpd interest will be
: 4000((1+(9÷12)/100)^5×12
remember to note that when you divide the rate by a value, you must multiply the value to your no. of months in this case