I personally look at the problem by saying there is a leap year every four years:
a. 2050-2008= 42 years (ok) but 42/4=10.5 (decimal - not a leap year)
b. 2054-2008= 46 yrs (not a multiple of 42 yrs) and 46/4 = 11.5 (decimal - not a leap year)
c. 2092-2008 = 84 yrs (multiple of 42 yrs - ok) and 84/4 =21 so a leap year ANSWER
d. 2112-2008=104 years (not a multiple of 42 years) but 104/4 = 26 so a leap year
e. 2120-2008=112 years (not a multiple of 42 years) but 112/4 = 28 (so a leap year)
another words, the comet will appear every 42 years from 2008: 2008, 2050,2092, 2134, 2176...
but it has to be a leap year - that occurs every 4 years: 2008,2012,2016,...
u want to find out when the above 2 series of years coincide in the answers
how do you know if it is a leap year? divide the number of years that have passed by 4 - if it is a decimal it is not divided evenly by 4 so is not a leap year.
the comet will appear every 42 years from 2008: 2008, 2050,2092, 2134, 2176... these are your only possible answer choices since the comet appears only every 42 years, but which of them is also a leap year ?
so u can rule out answers b, d and e cuz they are not even every 42 years so no comet appears
Now you know the answer has to be A. or C. Well A. is not a leap year cuz 42 years have passed but 42/4 = 10.5 decimal so not a leap year leap years occur every 4 years: 2008,2012,2016,2020,2024,2028,2032,2036,2040,2044,2048,2052 - notice 2050 is not a leap year.
C. is correct cuz comet appears every 42 years: 2008,2050,2092 so 2092 works. is 2092 a leap year? YES 2092-2008 = 84 years 84 is evenly divisible by 4= 21, so 21 groups of 4 years have passed or 84 years, so 2092 is a leap year. another words, 2092 is year in which the comet appears AND also a leap year.
C. is CORRECT!
