How would you work out 5mm as a radius on circumference

Which shows the pre image of triangle xyz

How many of the 250 grandparents in the population would you expect to prefer online shopping with merchant a? merchant a: 4 merchant b: 6 merchant c: 2 merchant d: 3 other: 5 none: 5 answer choices: a.about 4 b.about 8 c.about 40 d.about 21

Which ratios are equivalent to 10: 16? check all that apply. 30 to 48 25: 35 8: 32 5 to 15