I believe the acceleration would be 5m/s
All you would need to do is divide the final speed by the time it took to get there. I am only about 80 sure this answer is correct, so take my advise only if you feel comfortable.
Answer:
a) 25.5°(south of east)
b) 119 s
c) 238 m
Explanation:
solution:
we have river speed
=2 m/s
velocity of motorboat relative to water is
=4.2 m/s
so speed will be:
a)
=
+
solving graphically

=4.7 m/s
Ф=
=25.5°(south of east)
b) time to cross the river: t=
=
=119 s
c) d=
=(2)(119)=238 m
note :
pic is attached
1 Kilojoule [kJ] = 737.562 149 277 27 Foot pound force [ftlbf]