2 easy questions: Probability/Percentages and Digits

In the life sciences department, 65% of the total number of students watch the news on

television, 40% read a newspaper and 25% both read a newspaper and watch the news on

television. What percentage of the department's students do not watch the news on

television and do not read a newspaper?

(1) 0%

(2) 10%

(3) 20%

(4) 25%

My solution:

100 students.

40-25 = 15 only newspaper

65- 25 = 40 only TV

answer is 2.. 10%

not sure..

guess:

65+25 = 90?

100-90 is 10?

not sure...

DIGITS question:

25. A, B, C and D are letters representing different digits, so that ABCD is a four-digit

number.

Given: A·AB = CD

If we divide ABCD by the number AB, what three-digit number will be obtained?

(1) 101

(2) 1AB

(3) 11A

(4) 10A

answer 4

AB into ABCD..

start with a 1

CD is A^2B

and AB into A^2B is...? 0A

AB/AAB leave you with.. 1/A

not sure ..

THANKS IN ADVANCE

Re: 2 easy questions: Probability/Percentages and Digits

For the first question, there are just four groups. Those that just watch TV, those that just read, those that do both and those that do neither. You've worked out numbers for the first two and you are given the number for the third group. If all four total 100 you should be able to deduce the fourth. (It's easy to see what's going on if you draw a Venn diagram).

For the second question, get what's going on straight in your mind by working through a long division using actual numbers. Try for example 1236/12, 12's into 1 don't go, 12's into 12 go once etc.

Re: 2 easy questions: Probability/Percentages and Digits

Hello, jsvlad!

Quote:

25. $\displaystyle A, B, C, D$ are letters representing different digits,

. . .so that $\displaystyle ABCD$ is a four-digit number.

Given: .$\displaystyle A\cdot AB \,=\, CD$

If we divide $\displaystyle ABCD$ by the number $\displaystyle AB$, what three-digit number will be obtained?

. . $\displaystyle (1)\;101 \qquad (2)\;1AB \qquad (3)\;11A \qquad (4)\;10A$

Simply "do" the long division . . .

. . $\displaystyle \begin{array}{cccccc}&&&1 & 0 & A \\ && -- & -- & -- & -- \\ A\:\;\;B & | & A & B & C & D \\ && A & B \\ && -- & -- \\ &&&& C \\ &&&& 0 \\ &&&& -- \\ &&&& C & D \\ &&&& C & D \\ &&&& -- & -- \end{array}$

Re: 2 easy questions: Probability/Percentages and Digits

hello..

how did you pull that off with those awesome graphics/image? im impressed, i would like to knw..

q1

15+40+25 = 80

100-80 = 20

Quote:

Originally Posted by

**Soroban** Hello, jsvlad!

Simply "do" the long division . . .

. . $\displaystyle \begin{array}{cccccc}&&&1 & 0 & A \\ && -- & -- & -- & -- \\ A\:\;\;B & | & A & B & C & D \\ && A & B \\ && -- & -- \\ &&&& C \\ &&&& 0 \\ &&&& -- \\ &&&& C & D \\ &&&& C & D \\ &&&& -- & -- \end{array}$