Answer:
Area of circle A =113.14 mm²
Area of circle b = 314.29 mm²
Area of circle C = 452.57 mm²
Area of circle A = 254.57 mm²
2.25 times
Step-by-step explanation:
Area of a circle = nr²
where n = 22/7
r = radius
Circle A's radius = 6mm
Circle B's radius = 6mm + 4mm = 10mm
Circle C's radius = 10mm + 2mm = 12mm
Circle D's radius = 12mm - 3mm = 9mm
Area of circle A = (22/7) x 6² = 113.14 mm²
Area of circle b = (22/7) x 10² = 314.29 mm²
Area of circle C = (22/7) x 12² = 452.57 mm²
Area of circle A = (22/7) x 9² = 254.57 mm²
Number of times the area of circle D is greater than that circle A = Area of circle D / Area of circle A
254.57 mm² / 113.14 mm² = 2.25 times
<span>3 of the 20 toothbrushes are defective, so the initial probability of selecting a defective toothbrush on the first try is 3/20. After that, there will be 2 defective toothbrushes in the remaining 19, so the probability of selecting one of those on the 2nd try will be 2/19. To get the probability of those two events happening sequentially, we multiply the two probabilities. Thus (3/20)*(2/19) = 6/380 = 0.0157, or about 1.6%.</span>
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