Tham khảo tài liệu 'sat virtual reality iii explanations phần 2', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 15. C ọ g c o p CD Ư Here you re given that a and b are integers but you don t know whether they are positive or negative so there are a lot of possible values of a and b that fit the equation 2a 5b 15. One way to solve this one is to backsolve - to try each answer choice. Plug in the given value for b and see if the equation works. If you start with choice C which is a good idea when backsolving you re in luck here. If b were equal to 2 the equation 2a 5b 15 would be 2a 10 15 or 2a 5 or a . But you re given that a is an integer so a cannot possibly be so b 2 doesn t work and choice C is correct. You might have noticed that in the equation 2a 5b 15 you have an even number 2a plus another number 5b being equal to an odd number 15. An even number plus an even number equals an even number and an even number plus an odd number equals an odd number so the expression 5b must be an odd number. If 5b is an odd number then b must be an odd number since odd X odd odd and odd X even even . Therefore the correct answer choice is the one even number again choice C . 16. B Since you re given that y is between -1 and 0 why not pick an appropriate number for y and plug it into each answer choice Try y - -2. Then choice A is 2_ 1 2_ 1 1 _ 1 B_1. nx y2 -2 4 B is 1 - y 1 - -2 1 2 C is 1 y 1 -2 12 D is 2y 2 - 2 -1 and E is y 2 nh i 3- - 2 I 2 J 2 Choice B is the greatest. 17. C A good way to solve this question is by making yourself a little table. Each employee is described by two different things. Each one is a woman or a man and each one either drives to work or takes public transportation. So make this table W M D P SAT Virtual Reality III 1 2 In this table each box will contain the number of employees having the two appropriate attributes. For example the box in the lower right-hand corner is the number of men who take public transportation. We can also put numbers in the margins. For example we can put the number of women in the company below the box in the lower .
