# Thread: 2 easy questions: Probability/Percentages and Digits

1. ## 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

AB into ABCD..

CD is A^2B
and AB into A^2B is...? 0A
AB/AAB leave you with.. 1/A

not sure ..

2. ## 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.

3. ## Re: 2 easy questions: Probability/Percentages and Digits

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

Given: . $A\cdot AB \,=\, CD$
If we divide $ABCD$ by the number $AB$, what three-digit number will be obtained?

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

Simply "do" the long division . . .

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

4. ## 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

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