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Standards are essential in science. For example, the meter is defined as the distance light travels in a vacuum in 1/299,792,458 of a second. The standard for the kilogram has long been a platinum-iridium weight stored in Sevres, France. However, recent measurements indicate that the kilogram standard has been losing weight. Since the last time the weight was taken out (more than 20 years ago), it appears to have lost about 50 micrograms (roughly the weight of a grain of sand). Since the kilogram is the basis for other units of measure (such as the joule) this could be a real problem. Scientists are working on a new standard, but they have yet to establish one. You can learn more about the problems with the current kilogram standard here.

7/8 > Link of the Day

Read the following question and then select the correct answer.


Remember to read the question carefully. Some students panic when they see a complicated diagram or chart. Every problem on the SAT has a solution that you can reach without any particular, specialized knowledge (though you do still need to memorize basic math formulas). Slow down and reread the problem carefully; make sure that you understand what the question is actually asking.

math image

The table above shows the attendance at the home games of the Central High School football team. If the median attendance for the five games was 456 and no two games had the same attendance, what is the greatest possible value for n?

You are looking for the greatest possible value for n. Recall that the median is the middle number (when a list of numbers is arranged in order from smallest to largest or largest to smallest). So, the first step is to arrange the numbers in order. Now you have

550
508
456
399

and somewhere in that list is n. You know that 456 is the median. That means that n must be less than 456 (in order to make 456 the median number). In other words, the numbers must go in this order

   550
   508
   456
399  n

That means the largest possible value for n is 455 (because it must be less than 456). Now, look at the answers and select the one that matches your prediction.

(A) 400
(B) 455
(C) 457
(D) 478
(E) 549

The correct Answer Choice is (B).

On sat.collegeboard.org 54% of the responses were correct.

For more help with math visit www.myknowsys.com.