Then a quarter- scale turbine model tested under a head of 10 m must run at

Question

If the full- scale turbine is required to work under a head of 30 m and to run at 428 rpm, then a quarter- scale turbine model tested under a head of 10 m must run at                               

(a) 143 rpm                  (b) 341 rpm

(c)  428 rpm                 (d) 988 rpm