neokeynesian

10-29-2004, 06:13 AM

Please see the attachment

View Full Version : pp question -- integer & percent

neokeynesian

10-29-2004, 06:13 AM

Please see the attachment

lmtuan

10-29-2004, 06:54 AM

we have 800 integers between 200 and 999.

The number of the integers between 200 and 999, inclusive ,begin with an 8 or a 9 and end with an odd digit is: 2 * 10 * 5 = 100.

Thus, the percent of the integers between 200 and 999, inclusive ,begin with an 8 or a 9 and end with an odd digit is (100/800) * 100% = 12.5%.

Answer: C

The number of the integers between 200 and 999, inclusive ,begin with an 8 or a 9 and end with an odd digit is: 2 * 10 * 5 = 100.

Thus, the percent of the integers between 200 and 999, inclusive ,begin with an 8 or a 9 and end with an odd digit is (100/800) * 100% = 12.5%.

Answer: C

vn_snoopy

10-30-2004, 02:37 AM

What do they mean by "between"? Do they count the two numbers at the beginning and the end (which are 200 and 999) as "between" 200 and 999?

If they do not, we have 798 numbers between 200 and 999, and the approximation percentage is also 12.5%.

About the number required between 200 and 999: we have 2 choices for the hundreds digit (8 and 9), 5 choices for the units digit (the 5 odd numbers: 1,3,5,7,9), and 10 choices for the tens digit (0-9). Hence, we have 2*5*10 choices... as lmtuan has stated. ;)

If they do not, we have 798 numbers between 200 and 999, and the approximation percentage is also 12.5%.

About the number required between 200 and 999: we have 2 choices for the hundreds digit (8 and 9), 5 choices for the units digit (the 5 odd numbers: 1,3,5,7,9), and 10 choices for the tens digit (0-9). Hence, we have 2*5*10 choices... as lmtuan has stated. ;)

calm_J

11-06-2004, 10:43 AM

here it's

the count of no. between 200 and 999 inclusive is 999-200+1 (this one because he said inclusive) which will equal 800 No.

no we have only 200 No. out of those 800 that have 8 or 9 as a start digit.

from those 200 No we are searching for the folowing criteria

8_1

8_3

8_5

8_7

8_9

9_1

9_3

9_5

9_7

9_9

this means two things

1- in each 10 consecutive No. 's between 800 -999 there exists 5 No. that meets our criteria

2- we have 20 tens in those 200 No.

then 20 * 5 = 100 No. as a total that meets our criteria

then the percentage is 100/800 *100% = 12.5

the count of no. between 200 and 999 inclusive is 999-200+1 (this one because he said inclusive) which will equal 800 No.

no we have only 200 No. out of those 800 that have 8 or 9 as a start digit.

from those 200 No we are searching for the folowing criteria

8_1

8_3

8_5

8_7

8_9

9_1

9_3

9_5

9_7

9_9

this means two things

1- in each 10 consecutive No. 's between 800 -999 there exists 5 No. that meets our criteria

2- we have 20 tens in those 200 No.

then 20 * 5 = 100 No. as a total that meets our criteria

then the percentage is 100/800 *100% = 12.5