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lys-0071 [83]
2 years ago
15

An in ground rectangular pool has a concrete pathway surrounding the pool. if the pool is 16 feet by 32 feet and the entire area

of the pool including the walkaway is 924 ft^2, find the width of the walkway
Mathematics
1 answer:
Anastasy [175]2 years ago
7 0
1. Let's call:
 
 x: the width of the walkway.
 b: 2x+16 (there is a widht "x" of the walkway on each side).
 h: 2x+32  (there is a widht "x" of the walkway on each side).
 A: 924 ft^2 ( the area of the pool of including the walkway).
 
 2. The area of a rectangle is:  
 
 A=(b)(h)
 
 b: the base of the rectangle (2x+16)
 a: the height of the rectangle (2x+32)

 3. Then, we have a quadratic equation:
 
 924=(2x+16)(2x+32)
 4x^2+64x+32x+512-924=0
 4x^2+96x-412=0
 
 4. We apply the quadratic formula to find the value of "x":
 
 x=(-b±√(b^2-4ac))/2a
 
 x=3.71
 
 The answer is: The width of the walkway is 3.71 ft

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Answer:

  8.1 hours

Step-by-step explanation:

A model of the fraction remaining can be ...

  f = (1/2)^(t/37) . . . . t in hours

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  0.86 = 0.5^(t/37)

  log(0.86) = (t/37)log(0.5)

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The quality control manager at a light bulb factory needs to estimate the mean life of a batch (population) of light bulbs. We a
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Answer:

<em>a)95%  confidence intervals for the population mean of light bulbs in this batch</em>

(325.5 ,374.5)

b)

<em>The calculated value Z = 4 > 1.96 at 0.05 level of significance</em>

<em>Null hypothesis is rejected </em>

<em>The manufacturer has not right to take the average life of the light bulbs is 400 hours.</em>

Step-by-step explanation:

Given sample size n = 64

Given  mean of the sample x⁻ = 350

Standard deviation of the Population σ = 100 hours

The tabulated value Z₀.₉₅ = 1.96

<em>95%  confidence intervals for the population mean of light bulbs in this batch</em>

<em></em>(x^{-} - Z_{\frac{\alpha }{2} } \frac{S.D}{\sqrt{n} } , x^{-} + Z_{\frac{\alpha }{2} }\frac{S.D}{\sqrt{n} } )<em></em>

<em></em>(350 - 1.96\frac{100}{\sqrt{64} } , 350 + 1.96\frac{100}{\sqrt{64} } )<em></em>

(350 -24.5, 350 +24.5)

(325.5 ,374.5)

b)

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Given mean of the Population μ = 400

Given sample size n = 64

Given  mean of the sample x⁻ = 350

Standard deviation of the Population σ = 100 hours

<u><em>Null hypothesis</em></u> : H₀:The manufacturer has right to take the average life of the light bulbs is 400 hours.

μ = 400

<u><em>Alternative Hypothesis: H₁:</em></u> μ ≠400

<u><em>The test statistic </em></u>

Z = \frac{x^{-}-mean }{\frac{S.D}{\sqrt{n} } }

Z = \frac{350 -400}{\frac{100}{\sqrt{64} } }

|Z| = |-4|

The tabulated value   Z₀.₉₅ = 1.96

The calculated value Z = 4 > 1.96 at 0.05 level of significance

Null hypothesis is rejected.

<u><em>Conclusion:</em></u>-

The manufacturer has not right to take the average life of the light bulbs is 400 hours.

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