The company has to study 199 machines.
In statistics, the standard deviation is a measure of the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean of the set, while a high standard deviation indicates that the values are spread out over a wider range.
It is given that;
Margin of error E = 0.7
Confidence interval 98% = 1-0.98 = 0.02
Standard deviation = 6 hours
Number of MRI machines needed per day n, = [(z alpha/2 * SD)/E]²
Z alpha/2 = 1.645 at alpha = 0.1
Inputting these values into n we have that
[(1.645*6)/0.7]²
= 14.1²
= 198.81 is approximately equal to 199
The company has to study 199 machines.
To know more about standard deviation visit: brainly.com/question/475676
Answer: see proof below
<u>Step-by-step explanation:</u>
(3x² -7x⁴) from (5x² - 3x⁸)
= 5x² - 3x⁸ - (3x² -7x<span>⁴ )
= </span> 5x² - 3x⁸ - 3x² + 7x<span>⁴
= </span>- 3x⁸ + 7x⁴ + 5x² <span>- </span><span>3x²
</span>
= - 3x<span>⁸ </span>+ 7x⁴ + 2x<span>²</span>
