The mass of the rider 1 is 4 g.
Rider is a metallic wire piece which is of certain mass and can be bent . It can move the beam of the Paul Bunge Balance.
The riders are the sliding pointers positioned on top of the beams to show the pan and beam weight in grams.
The mass of the rider 1 is obtained by subtracting mass of riders as show below.
mass of rider 1 = mass of object - (mass of rider 2 + mass of rider 3)
mass of rider 1 = 694 g - (600 g + 90 g)
mass of rider 1 = 694 g - 690 g
mass of rider 1 = 4 g
Thus, the mass of the rider 1 is 4 g.
Learn more about use of riders in mass measurement here: https://brainly.com/question/1747339
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