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Pattern Problems

Link of the Day

How important is history?  Should people take more responsibility for solving problems that affect their communities or the nation in general?  That second question is a previous SAT essay question.  Before you answer it, read here and here about how the people of Mali reacted to a threat against manuscripts as old as the 13th century.  What important themes do you see in these articles that would be easy to write about as a current event example?  Write down details and facts that could help to support an opinion on a broad topic.


Arithmetic: Pattern Problems

Read the following SAT test question and then select the correct answer. 

Work each math problem by reading the question carefully and identifying the bottom line.  Then assess your options and choose the most efficient method to attack the problem.  When you have an answer, loop back to make sure that you finished all of the steps to match your bottom line.

If it is now 4:00 p.m. Saturday, in 253 hours from now, what time and day will it be? (Assume no daylight saving time changes in the period.)

Bottom Line: 253 hours from now = ?

Assess your Options: You could try to count the hours elapsed from the answer choices, but that will be time consuming if you don’t guess the right one first and end up working the problem five times.  Instead, use logic to methodically work through this problem.

Attack the Problem:  You are given 253 hours, but you know that there will also be a change in the day.  There are only 24 hours in a day.  Find out how many days there are in this time period by dividing.  Now, this problem is similar to the pattern problems in your Knowsys book.  You want to know how many days and hours have passed.  Instead of dividing with your calculator, use long division to find out how many days pass and how many hours remain. 253 ÷ 24 is 10 with a remainder of 13.  That means that there are 10 days and 13 hours that pass.

Continue to think about this logically.  If it is 4:00 p.m. on Saturday and a week passes, it will be the same day.  So 7 days will get you back to the same place.  Then you have 3 of your 10 days still to go.  Count 3 days from Saturday, (Sun, Mon, Tues), and you are now at 4:00 p.m. on Tuesday.

That accounts for all of the days that have passed, but you still have 13 hours.  If you add 12 hours to 4:00 p.m., it becomes 4:00 a.m. on the next day, Wednesday.  Add 1 more hour and you get 5:00 a.m. on Wednesday. 

Loop Back:  You accounted for all of the 253 hours by counting out 10 days and 13 hours.  Look down at your answer choices.

(A) 5:00 a.m. Saturday
(B) 1:00 a.m. Sunday
(C) 5:00 p.m. Tuesday
(D) 1:00 a.m. Wednesday
(E) 5:00 a.m. Wednesday

The correct answer is (E).


On sat.collegeboard.org, 49% of the responses were correct.

For more help with SAT math, visit www.myknowsys.com!