Justin is getting a salary raise of $5,000. He wants to put this money in a relatively safe investment. Which investment has the
2 answers:
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Answer:
No <em>real</em> solutions (or has two complex roots)
Step-by-step explanation:
The discriminant, <em>b</em>² - 4<em>ac</em>, is the expression (<u><em>radicand </em></u>) of the quadratic equation:
.
The value of the discriminant determines the <u>nature</u> and the <u>number of solutions</u> given by the quadratic equation.
A discriminant with a negative value (or b² - 4ac < 0 ) means that the quadratic equation has no real solutions or two complex solutions. Quadratic equations with a negative discriminant also have no x-intercepts; thus, its graph will not cross the x-axis.
<h2><u>Answer with explanation</u>:</h2>
Let be the average life of light bulbs.
As per given , we have
Null hypothesis :
Alternative hypothesis :
Since is right-tailed and population standard deviation is also known, so we perform right-tailed z-test.
Formula for Test statistic :
where, n= sample size
= sample mean
= Population mean
=population standard deviation
For , we have
Using z-value table , Critical one-tailed test value for 0.06 significance level :
Decision : Since critical z value (1.5548) < test statistic (1.6180), so we reject the null hypothesis .
[We reject the null hypothesis when critical value is less than the test statistic value .]
Conclusion : We have enough evidence at 0.06 significance level to support the claim that the new filament yields a longer bulb life