1–15. Two boys find that they can balance each other on a plank if one sits six feet from the fulcrum and the other eight feet. The heavier boy weighs 120 pounds. How much does the  lighter  boy  weigh? 1. 90 lb 2. 106  lb 3. 112  lb 4. 114  lb 1–16. With the aid of shown in figure the 1D, pipe wrench how many pounds of effort will you need to exert to overcome a resistance of 900 pounds? 1. 25 lb 2. 50 lb 3. 75 lb 4. 100  lb Questions  1-17  and  1–18  are  related o to a 300–pound load of firebrick stacked on a wheelbarrow. Assume that the weight of the firebrick is centered at a point and the barrow axle is 1 1/2 feet forward of the point. 1–17. 1-18. 1-19. If a Seaman grips the barrow handles at a distance of three feet from the point, how many total pounds will the Seaman have to lift to move the barrow? 1. 65 lb 2. 100  lb 3. 150  lb 4. 300  lb If a Seaman grasps the handles 3 1/2 feet from the point where the weight  is  centered,  how  many  pounds of effort will be exerted? 1. 50 lb 2. 90 lb 3. 100  lb 4. 120 lb In lever problems, the length of the effort arm multiplied by the effort is equal to the length of the 1. resistance  arm  multiplied  by the effort 2. resistance  arm  multiplied  by the  resistance 3. effort  arm  multiplied  by  the resistance  arm 4. effort arm multiplied by the resistance 1-20. The length of the effort arm in figure 1E is equal to the length of the 1. curved line from A to C 2. curved line from A to D 3. straight line from B to C 4. straight line from B to D 3