6x7 = 42
7+6 = 13
I hope this helps!
For the first three balls that are chosen, the probability would be found by the following expression: 9/15*8/14*7/13 = 12/65 The numerator decreases since the number of new balls is decreasing with each one that is removed. The denominator decreases since the total number of tennis balls in the box is being decreased. For the second time that balls are chosen, the following expression is used: 6/15*5/14*4/13 = 10/273 The numerator starts with 6 since there are now fewer balls that are unused due to the ones previously have been used. These two fractions are then multiplied to find the total probability that none of the 6 balls were used. 12/65*10/273 = 8/1183
By the Pythagorean theorem,
.. x^2 +(x -46)^2 = (x +4)^2
.. 2x^2 -92x +2116 = x^2 +8x +16
.. x^2 -100x +2100 = 0
.. (x -50)^2 -400 = 0
.. x = 50 ±20 . . . . . only x=70 makes any sense in the problem
The height, x, of the tree is 70 meters.
Its the second choice down. x is an element of the intersection of B and C. A is not part of that, and since B and C overlap, it's the intersection, not the union (U).
