To draw a heart, one would be choosing 1 card of 13 possible hearts, and 0 from the remaining 39 non-hearts. With respect to the entire deck, one would be choosing 1 card from 52 total cards. So the probability of drawing a heart is

When Michelle replaces the card, the deck returns the normal, so the probability of drawing any card from a given suit is the same,
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. In other words, drawing a spade is independent of having drawn the heart first.
So the probability of drawing a heart, replacing it, then drawing a spade is
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.
190*76 is equal to 14440.
use midpoint equation
radius = distance between midpoint and one of the endpoints.
midpoint: (3+5)/2, (2+6)/2, (5+7)/2 = (4,4,6)
equation of sphere: (x-4)^2 + (y-4)^2 + (z-6)^2 = r^2
square distance between midpoint and one of the endpoints.
r^2 = 6
Equation: (x-4)^2 + (y-4)^2 + (z-6)^2 = 6
(b - 4z)/7 = a
b - 4z = 7a
b = 7a + 4z
Answer: b = 7a + 4z
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