A speaker was so boring that one-half of the audience left after a few minutes. Five minutes later, one-third of the remaining audience left. Ten minutes later, one-fourth of those remaining left, leaving only nine people in the audience. How many people were in the audience at the beginning of the lecture?
2006-10-10 23:27:52 · 10 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
let the no be x.We will now list
people remaining (after each interval.)
After few minutes=x/2
After 5 min.=2/3*x/2=x/3
After 10min.=3/4*x/3=x/4
Therefore x/4=9
x=36
Verify
after few min.=18
after 5min.=12
after10 min.=9
ok
2006-10-10 23:40:37 · answer #1 · answered by openpsychy 6 · 0⤊ 0⤋
36
2006-10-11 06:32:15 · answer #2 · answered by jen jo 2 · 0⤊ 0⤋
Ans: 36
x * 1/2 * 2/3 * 3/4 =9
x=36(no. of audience at 1st)
*=mutiply
2006-10-11 06:35:39 · answer #3 · answered by mojo 1 · 0⤊ 0⤋
36
If 1/2 of the people left, then 1/2 remain.
If 1/3 of the people left, then 2/3 remain.
If 1/4 of the people remain, then 3/4 remain.
The equation will then be:
3/4(2/3(1/2x))=9
1/4x=9
x=36
2006-10-11 06:30:38 · answer #4 · answered by Melody 3 · 0⤊ 0⤋
x-1/2x-1/3(x-1/2x)-1/4(x-1/2x-1/3x+1/6x)=9
x-1/2x-1/3x+1/6x-1/4(x-1/2x-1/3x+1/6x)=9
x-1/2x-1/3x+1/6x-1/4x+1/8x+1/12x-1/24x=9
x is common
x(1-1/2-1/3+1/6-1/4+1/8+1/12-1/24)=9
x/24(12-8+4-6+3+2-1)=9
x/24*6=9
x/4=9
x=36 (total no. of audience in the beginning)
2006-10-11 07:08:20 · answer #5 · answered by ain 1 · 0⤊ 0⤋
36 PEOPLE WERE PRESENT IN THE BEGINNING.
2006-10-11 06:39:47 · answer #6 · answered by cooldude 3 · 0⤊ 0⤋
36 absolutely...
2006-10-11 06:39:26 · answer #7 · answered by Arunagiri K 2 · 0⤊ 0⤋
37!!!
You are forgetting the speaker himself.
2006-10-11 06:50:26 · answer #8 · answered by Chelin Fdez. 2 · 1⤊ 0⤋
216.
2006-10-11 06:42:40 · answer #9 · answered by anildesk 3 · 0⤊ 1⤋
(1/2)*(2/3)*(3/4)*X=9
(6/24)X=9
X/4=9X=9*4
X=36
2006-10-11 07:11:06 · answer #10 · answered by safrodin 3 · 0⤊ 0⤋