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In a box, there is 1 more green pens than black pens. The probability of taking 2 black pens is 0.2 . How many pens are in the box?

g = b+8g+b = p = 2b+1(b/p) x (b-1)/(p-1) = 1/5(b^2 - b)/(p^2 - p) = 1/5sub in p= 2b+1(b^2 - b)/(4b^2 + 2b) = 1/55b^2 - 5b = 4b^2 + 2bb^2 -7b = 0b = 7 or b = 0 (cannot be 0 as 2 pens must be taken)p = 2(7) + ...
JL
Answered by James L. • Maths tutor
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A bag with 750 balls is comprised of 300 red, 200 blue and 250 green. What is the probability of three green balls being in succession, providing the ball is put back between each turn.

1/27 (1/3 x 1/3 x 1/3)
JS
Answered by Jack S. • Maths tutor
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write 17/3 as a proper fraction

5 and 2/3
JS
Answered by Jack S. • Maths tutor
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Explain the process of using de Moivre's Theorem to find a trigonometric identity. For example, express tan(3x) in terms of sin(x) and cos(x).

Identify de Moivre's Theorem: (cos(x) + isin(x)) n = cos(nx) + isin(nx) 2) Deduce the correct value of n for the given problem. In this example we set n=3 3) Expand the LHS (usually by a binomial expansion)....
OL
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There is a Ferris wheel where the passengers are placed 10m away from the centre. At what speed must they be moving in order for them to feel completely weightless at the top of the wheel.

In order for the passenger to feel weightless, they must have a vertical acceleration equal to the acceleration due to gravity, i.e. they must be accelerating downward at a rate of 9.81m/s 2 . acceleration =...
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