Answer:
The measure of arc EBC is 220°
Step-by-step explanation:
step 1
Find out the measure of angle COB
we know that
m∠COB+m∠DOC=90° -----> given problem
we have that
m∠DOC=m arc DC -----> by central angle
m arc DC=50°
so
m∠DOC=50°
Find m∠COB
m∠COB+50°=90°
m∠COB=40°
step 2
Find out the measure of arc BC
we have that
m arc BC=m∠COB -----> by central angle
m∠COB=40°
therefore
m arc BC=40°
step 3
Find out the measure of arc EBC
we know that
m arc EBC=m arc EB+m arc BC
m arc EB=180° -----> because the diameter divide the circle into two equal parts
so
m arc EBC=180°+40°=220°
Answer: 49.85%
Step-by-step explanation:
Given : The physical plant at the main campus of a large state university recieves daily requests to replace florecent lightbulbs. The distribution of the number of daily requests is bell-shaped ( normal distribution ) and has a mean of 61 and a standard deviation of 9.
i.e. 
and 
To find : The approximate percentage of lightbulb replacement requests numbering between 34 and 61.
i.e. The approximate percentage of lightbulb replacement requests numbering between 34 and 
.
i.e. i.e. The approximate percentage of lightbulb replacement requests numbering between 
and 
. (1)
According to the 68-95-99.7 rule, about 99.7% of the population lies within 3 standard deviations from the mean.
i.e. about 49.85% of the population lies below 3 standard deviations from mean and 49.85% of the population lies above 3 standard deviations from mean.
i.e.,The approximate percentage of lightbulb replacement requests numbering between and = 49.85%
⇒ The approximate percentage of lightbulb replacement requests numbering between 34 and 61.= 49.85%
-- You have two angles.
-- They're complementary . . . they add up to 90 degrees.
-- One is 4 times as big as the other one.
___________________________________________
-- The smaller angle has 1 share of the 90 degrees.
-- The bigger angle has 4 shares of the 90 degrees.
-- (The smaller one is 1/4 the size of the bigger one.
The bigger one is 4 times the size of the smaller one.)
-- When you add them together, you get 5 shares, totaling 90 degrees.
-- What's the size of each share ? It's 90/5 = 18 degrees.
-- The smaller angle gets one share . . . 18 degrees.
-- The bigger angle gets 4 shares. (4 x 18) = 72 degrees.
____________________________________
Check:
-- Is the small one 1/4 the size of the big one ? 18/72 = 1/4 Yes.
-- Are they complementary ? Do they add up to 90 degrees ?
18 + 72 = 90 Yes.
yay !
