kelseydavid69

21.07.2019 • 

Mathematics

Acompany produces steel rods. the lengths of the steel rods are normally distributed with a mean of 108.7-cm and a standard deviation of 0.6-cm. for shipment, 22 steel rods are bundled together. find the probability that the average length of rods in a randomly selected bundle of steel rods is less than 109.1-cm. round to 4 decimal places. answers obtained using exact z-scores or z-scores rounded to 2 decimal places are accepted.

Ответ:

bellebug6208

14.03.2022

Mathematics

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Let x be the lengths of the steel rods and X ~ N (108.7, 0.6)

To get the probability of less than 109.1 cm, the solution is computed by:

z (109.1) = (X-mean)/standard dev

= 109.1 – 108/ 0.6

= 1.1/0.6

=1.83333, look this up in the z table.

P(x < 109.1) = P(z < 1.8333) = 0.97 or 97%

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Ответ:

jimmyjimjim

29.05.2022

Mathematics

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You can do these by two Methods.
1) Splitting middle term
2) Quadratic formula

I am doing with first method

6)x^2-6x+8=0
x^2-(4x+2x)+8=0
x^2-4x-2x+8=0
x(x-4)-2(x-4)=0
(x-4) * (x-2) =0
x= +4 or +2

7) x^2-9x/4-25=0
4x^2-9x-100=0

D=√b^2-4ac
D= √81-4*4*-100
D√1681
D= 41
X= 9+ 41/ 8 OR 9-41/8
X= 50/8 OR -4

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