Hi,
We know that time period of pendulum ofllength with net vertical accelerationanetis given by

y=kt^2

=d^2y/dt^2=2k

a=2m/s^2

T1=2pie under root(g/l)

T2=2pie under root(l/g+ay)

(T1/T2)^2=(g+ay)/g

Using the values we get that

(10+2)/10=6/5=1.2