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2 years ago

The average of 3, 15, and my number is 40. What is my number? I'll give 30 points!

Mathematics

1 answer:

stepan [7]2 years ago

3 0

Answer:

102

Step-by-step explanation:

The average is calculated using

average = $\frac{totalscore}{count}$

let your score be x, then

$\frac{3+15+x}{3}$ = 40 ( multiply both sides by 4 )

18 + x = 120 ( subtract 18 from both sides )

x = 102 ← your number

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2 years ago

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$\sin^2 (\frac{\pi}{4} - \alpha) = \frac{1}{2}(1 - \sin 2\alpha)$

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$\dfrac{1 - \cos [2(\frac{\pi}{4} - \alpha)]}{2} = \frac{1}{2}(1 - \sin 2\alpha)$

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