<span>4×2-z=7
⇒ 8 - z = 7
⇒ 8 - 7 = z
⇒ 1 = z
</span>
X is equivalent to 200. (credit to suspho)
Answer:
a) 54 mph to 144 mph
Step-by-step explanation:
We don't know the shape of the distribution, so we use Chebyshev's Theorem to solve this question. It states that:
At least 75% of the measures are within 2 standard deviations of the mean.
At least 89% of the measures are within 3 standard deviations of the mean.
At least eight-ninths of the player's serves.
8/9 is approximately 89%
So
Mean: 99, standard deviation: 15
99 - 3*15 = 54
99 + 3*15 = 144
So the correct answer is:
a) 54 mph to 144 mph
It is either A or C just incase you needed an answer quickly
