To answer problems like this you have to use binomial:
P (x > 1) = 1 – p (0
< x < 1) > .7
So:
1 – p (0) – p (1) >
.7
1 – (3/ 4) ^n – (3/ 4)
^n (n – 1 ) (1/ 4) > .7
Therefore n > 5.185,
and the smallest value of n so that we can satisfy the given condition is 6
(rounded up)
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The arc length of AB is 8 m (app.)
Explanation:
Given that the radius of the circle is 8 m.
The central angle is 60°
We need to determine the arc length of AB
The arc length of AB can be determined using the formula,

Substituting central angle = 60° and circumference = 2πr in the above formula, we get,

Simplifying the terms, we get,

Dividing, we get,

Hence, the arc length is approximately equal to 8.
Therefore, the arc length of AB is 8 m