Mathematics, 03.04.2021 22:50 anggar20

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Answer from: xcasta213

9514 1404 393

136

Step-by-step explanation:

The attached chart shows the result of using the numbers in the problem statement to calculate the percentage of the population in each category.

95% accuracy on infected individuals is assumed to mean that 95% of the 2% who are infected return a positive test result. The other 5% return a negative test result.

Similarly, 90% accuracy on uninfected individuals is assumed to mean that 90% of the 98% who are not infected will return a negative test result, and the remaining 10% of those 98% will return a (false) positive test result.

Then of the 11.7% who return a positive test result, only 1.9% are actually infected. This fraction is a/b = 19/117, so ...

a + b = 19 + 117 = 136

_____

Additional comment

When forming ratios of percentages, one must be very clear about the base of the percentage. Above, the base for every percentage is the entire population of mathletes. The fraction 19/117 is the fraction of those who tested positive that are actually infected (about 16.2% of positives).

Answer from: Quest

the answer on e2020 is

4/5

3/5

4/3

step-by-step explanation:

Answer from: Quest

Intersecting secant-tangent theorem states that if a tangent segment and a secant segment are drawn to a circle from an exterior point, then the square of the measure of the tangent segment is equal to the product of the measures of the secant segment and its external secant segment.so to break it down: 1. pq acts as the tangent and ps as the secant with an intersection at p.sr = 21rp = 3x + 3pq = 4x + 4following to equation: tangent squared = the two segments multiplied by each otherso (4x + 4) ^ 2 = (3x + 3) • (21) simplifies to 16x^2 - 31x - 47 = 0 or (16x - 47)(x + 1) x = -1 or x = 47/162. pq acts as the tangent and ps as the secant with an intersection at p (again! )sr = 16rp = xpq = 15(15) ^ 2 = 16 • x225 = 16xx = 225/163. the interesting chords are proportional to each other so a ratio is possible to set up: ap dp 10 3 + x = = —— = pc pb 8 xcross multiple to get 10x = (3 + x)(8)x = 12

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