That’s y u don’t know what u have until you lose it
2 answers:
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121 is big enough to assume normality and not worry about the t distribution. By the 68-95-99.7 rule a 95% confidence interval includes plus or minus two standard deviations. So 95% of the cars will be in the mph range
The question is a bit vague, but it seems we're being asked for the 95% confidence interval on the average of 121 cars. The 121 is a hint of course.
The standard deviation of the average is in general the standard deviation of the individual samples divided by the square root of n:
So repeating our experiment of taking the average 121 cars over and over, we expect 95% of the averages to be in the mph range
That's probably the answer they're looking for.
Answer:
36 laps Ronnie swim during practice .
Step-by-step explanation:
Let us assume that the laps that Ronnie swims be x .
Let us assume that the laps that Jackie swims be y .
As given
For every 3 laps that Jackie swims, Ronnie swims 4 laps.
i.e
3 × laps that Ronnie swims = 4 × laps that Jackie swims
3 × x = 4 × y
3x = 4y
Equation becomes
x + y = 63
Thus by using 3x = 4y .
Thus
4x + 3x = 63 × 4
7x = 252
x = 36
Put the value of x in the equation x + y = 63
36 + y = 63
y = 63 - 36
y = 27
Therefore the 36 laps Ronnie swim during practice .