Answer:
3 1/2
Step-by-step explanation:
[(8/10+7/10)+2]= [(15/10)+2] = (2 15/10) = (3 5/10) = (3 1/2)
A standard deviation is 2500 miles, so the range of 25,000 to 37,500 is 2 standard deviations below, and 3 standard deviation above the mean of 30,000.
We aren't assuming anything about the distribution, but we sort of have to assume a normal distribution in order to answer. When you don't know anything about a distribution, this is generally what you do.
The general rule for standard deviations is:
+/- 1 SD: +/- 34% of population, for a total of 68%
+/- 2 SD: Another 14% in either direction, for a total of 96% of population.
+/- 3 SD, Another 2% in either direction, which pretty much captures the entire distribution (4 standard deviations from the mean is incredibly rare/unlikely)
We have a range of +/- 1 SD, so we know that 68% percent o the tire 'population' is captured in the range. We also have one more standard deviation in both directions, so we add 28% to this number to get 96% of the population. We have a third standard deviation above the mean, so we add another 2% to arrive at 98% of the population.
Answer is 98% of all such tires.
Expanding 8x^3, we multiply 8*8 and x^3 by x^3 to get 64x^6. Since we know that the cube root of 64 is 4, we can separate that. Next, since you add exponents while multiplying, 6/3 is the exponent for the cube root of x^6=x^2. Therefore, your answer is 4x^2
Lara can read 10 chapters in 4 hours.
At this rate, she can read half that many chapters in half the time.
So she reads 5 chapters in 2 hours.
So Lara reads 10 chapters in 4 hours,
+ 10 chapters in 4 more hours,
+ 5 chapters in 2 more hours.
That's 25 chapters in total, and 10 hours in total, ya? :)
