1)	a)	9 ± 2.24, 9 ± 24.9%
	b)	1 ± 2.24, 1 ± 224%
	c)	15 ± 2.24, 15 ± 14.9%;  if c had no error, then it comes to ± 2.2360, so I would still round that to ± 2.24

2)	120