Students at Warlock High are allowed to sign up for one social studies class each year. The numbers in each grade level signing up for various classes for the next school year are given in the following table: Grade US History Civics World History Economics Total
10th 75 10 125 5 215
11th 130 85 75 60 350
12th 35 150 50 105 340
Total 240 245 250 170 905

Part A: What is the probability that a student will take Civics?

Part B: What is the probability that a 10th-grader will take either US History or World History?

Part C: What is the probability that a student will take Economics given that he or she is in the 10th grade?

Part D: Consider the events "A student takes Civics" and "A student is a 12th-grader." Are these events independent? Justify your answer.

light-year  

the distance that light travels in a vacuum in one year, equal to about 9.46 trillion km (5.88 trillion mi). light-years are used in measuring interstellar and intergalactic distances.  

parsec  

a unit of distance used in astronomy, equal to about 3.25 light years (3.08 × 1016 meters).  

parallax  

the apparent angular displacement of a celestial body due to its being observed from the surface instead of from the center of the earth (diurnal parallax or geocentric parallax) or due to its being observed from the earth instead of from the sun (annual parallax or heliocentric parallax)  

absolute magnitude  

the magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.  

apparent magnitude  

the magnitude of a celestial object as it is actually measured from the earth.  

redshift  

an increase in the wavelength of radiation emitted by a celestial body as a consequence of the doppler effect.  

the great thing about your imagination is that it doesn't have to make sense! if i were you i would be stuck in space, no communication with earth travelling around and around, you can only guess how long its been since your communication broke down. you land on an undiscovered planet, you do a scientific investigation examining the elements and conditions. you come across alien lifeforms.  

best of luck!