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1 year ago

Pada suatu deret geometri diketahui suku ke-3 = 18 dan suku ke-6 = 486. suku pertama pada deret tersebut adalah...

1 answer:

3 0

A . r^(3-1) = 18
a . r^2 = 18...... (i)

a . r^(6-1) = 486
a . r^5 = 486 ...... (ii)

dengan membuat perbandingan dari kedua persamaan diperoleh:
r^2/r^5 = 18/486
1/r^3 = 1/27
r^3 = 27
r = akar pangkat 3 dari 27
r = 3

dari persamaan <span>a . r^2 = 18...... (i)
a . 3^2 = 18
a . 9 = 18
a = 18/9 = 2</span>

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(b) P[Height of 25 year old man is above 6 feet 5 inches gives that he is above 6 feet] = P[X, $6ft$ $5in$ - X, $6ft$ ]

P[X > $6ft$ $5in$ I X > $6ft$ ] = P[X > 77 I X > 72]

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= $\frac{P[Z >2.4]}{P[Z>0.4]}$

= $\frac{1-P[Z\leq2.4] }{1-P[Z\leq0.4] }$

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