Triangle abc is such that ab=4 and ac=8 if m is the midpoint of bc and am=3, what is the length of bc?
1 answer:
This is an interesting question. I chose to tackle it using the Law of Cosines.
AC² = AB² + BC² - 2·AB·BC·cos(B)
AM² = AB² + MB² - 2·AB·MB·cos(B)
Subtracting twice the second equation from the first, we have
AC² - 2·AM² = -AB² + BC² - 2·MB²
We know that MB = BC/2. When we substitute the given information, we have
8² - 2·3² = -4² + BC² - BC²/2
124 = BC² . . . . . . . . . . . . . . . . . . add 16, multiply by 2
2√31 = BC ≈ 11.1355
AC² = AB² + BC² - 2·AB·BC·cos(B)
AM² = AB² + MB² - 2·AB·MB·cos(B)
Subtracting twice the second equation from the first, we have
AC² - 2·AM² = -AB² + BC² - 2·MB²
We know that MB = BC/2. When we substitute the given information, we have
8² - 2·3² = -4² + BC² - BC²/2
124 = BC² . . . . . . . . . . . . . . . . . . add 16, multiply by 2
2√31 = BC ≈ 11.1355
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Answer:
The calculated t- value = 1.09 > 3.19 at 0.025 level of significance
Null hypothesis is rejected
There is sufficient evidence to support the claim that the bags are underfilled
Step-by-step explanation:
<u><em>Step(i)</em></u>:-
Given the mean of the Population(μ) = 419 grams
The sample size 'n' =19
Given mean of the sample x⁻ = 412
Given variance of the sample S² = 784
S = √784 = 28
<u><em>Step(ii)</em></u>:-
<u><em>Null hypothesis: H₀</em></u>: There is no sufficient evidence to support the claim that the bags are underfilled.
<u><em>Alternative hypothesis: H₁:</em></u>
There is sufficient evidence to support the claim that the bags are underfilled.
Test statistic
t = -1.09
|t| = |-1.09|
<em>Degrees of freedom ν = n-1 = 19-1 =18</em>
<em>t₀.₀₂₅ = 3.19</em>
<u><em>Final answer:</em></u><em>-</em>
The calculated t- value = 1.09 > 3.19 at 0.025 level of significance
Null hypothesis is rejected
There is sufficient evidence to support the claim that the bags are underfilled