The greatest common factor of 42 and 72 is 6.
6 times 7 is 42. 6 times 12 is 72. There is no greater factor for both numbers except for 6.
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The sampling technique used when A scientist chooses twenty people at random from each class is stratified sampling.
<h3>What is
stratified sampling?</h3>
Stratified sampling can be described as the type of sampling method whereby the total population is been divided into smaller groups or strata.
This usually done to complete the sampling process, hence The sampling technique used when A scientist chooses twenty people at random from each class is stratified sampling.
Read more on the stratified sampling here:
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X^2 + y^2 - 2x + 7y + 1 = 0
(x^2 - 2x) + (y^2 + 7y) + 1 = 0
(x^2 - 2x + 1) + (y^2 + 7y) + 1 = 0+1
(x^2 - 2x + 1) + (y^2 + 7y + 49/4) + 1 = 0+1+49/4
(x - 1)^2 + (y + 7/2)^2 + 1 = 0+1+49/4
(x - 1)^2 + (y + 7/2)^2 + 1-1 = 0+1+49/4-1
(x - 1)^2 + (y + 7/2)^2 = 49/4
(x - 1)^2 + (y + 7/2)^2 = (7/2)^2
The final answer is choice B
