In an anniversary celebration of Marilyn Bell's 1954 feat -- she was the first person to swim across Lake Ontario -- a swimmer set out from the

In an anniversary celebration of Marilyn Bell's 1954 feat -- she was the first person to swim across Lake Ontario -- a swimmer set out from the shores of New York and maintained a velocity of 4m/s [N]. As the swimmer approached the Ontario shore, she encountered a cross-current of 2m/s [E 25degrees S]. Calculate her velocity with respect to the crowd observing from the beach (with respect to the ground)