Answer:
option (a) It will be closer to 30 than to 20
Step-by-step explanation:
Data provided in the question:
For sample 1:
n₁ = 10
variance, s₁² = 20
For sample 2:
n₂ = 15
variance, s₂² = 30
Now,
The pooled variance is calculated using the formula,
on substituting the given respective values, we get
or
= 26.0869
Hence,
the pooled variance will be closer to 30 than to 20
Therefore,
The correct answer is option (a) It will be closer to 30 than to 20
Answer:
6.667 ft/s
Step-by-step explanation:
Given
Height of street light = 15ft
Height of man = 6ft
Speed away from pole = 4ft/s
Let x represents the distance between the man and the pole, and Let y represents the distance between the tip of the man's shadow to the pole.
This forms a similar triangle (see attachment below).
From similar triangles, we have
(y - x)/6 = y/15 ----- Solve equation
15(y - x) = 6 * y
15y - 15x = 6y ---- Collect Like Terms
15y - 6y = 15x
9y = 15x --- divide through by 9
y = 15x/9
y = 5x/3 ---- differentiate with respect to time, t
dy/dt = 5/3 dx/dt
dx/dt represents rate of change of distance per time = 4ft/s
while dy/dt represents rate of movement of his shadow tips
dy/dt = 5/3 * 4
dy/dt = 20/3 = 6.667 ft/s
