MATEMATIK & MACAM-MACAM - Jom Selesaikan Brain Teasers :)

tahihidungmasin · Post time 13-3-2013 11:53 AM

QUESTION 1 (SENANG)
If there are 24 people at a party and each person shakes abother person's hand, how many handshakes are there?

QUESTION 2 (SUSAH SIKIT)
How many integers between 10 and 100 are divisble by 3?

QUESTION 3 (SUSAH)
It takes Ahmad 4 hours to do a job. It takes Ali 2 hours to do the same job. How many such jobs could they do together in 4 hours?

Last edited by dauswq on 30-3-2013 01:19 AM

mamiayu · Post time 13-3-2013 12:07 PM

Q1) 23 x24= 552
Q2) 30
Q3) 3

tahihidungmasin · Post time 13-3-2013 12:50 PM

mamiayu posted on 13-3-2013 12:07 PM
Q1) 23 x24= 552
Q2) 30
Q3) 3

Answer 1 = salah

Answer 2 = betul
From 10 to 100, you have 12, then 15, etc., up to 99
This is 4 x 3, 5 x 3, up to 33 x 3.
So there are 33 - 4 + 1 = 30 integers.

Answer 3 = betul
In 4 hours Ahmad can do one job, and in 4 hours Ali can do two jobs. So 3 jobs.

tahihidungmasin · Post time 13-3-2013 01:04 PM

PART II

QUESTION 1 (SUSAH SIKIT)
A survey of 50 people who can write showed that 20 could write only with their left hand and 10 could write with either hand.
How many could write with their right hand?
(a) 30 (b) 20 (c) 25 (d) 10 (e) 40

QUESTION 2 (SENANG)
The average of the number 10 and some unknown number, x, is divided by the sum of 10 and x. The result is 1/2.
What is the value of x?

QUESTION 3 (SUSAH SANGAT)
Jane is 3 times as old as Ann; three years ago, Ann was a year younger than Joyce is now.
If Ellen is twice as old as Ann, list the four girls in descending age order?

GOOD LUCK!!!

ira79 · Post time 13-3-2013 02:14 PM

Part 2,

1) 50 - 20 = 30 answer is (a) taking right hand only + either hand
2) [(10+x)/2]/(10+x)=1/2, then multiply both side dgn 10+x, dapat (10+x)/2 =(10+x)/2, then dapat 10+x = 10+x.. apa punya soalan nih?
3) Jane, Ellen, Ann, Joyce..

tahihidungmasin · Post time 13-3-2013 02:25 PM

ira79 posted on 13-3-2013 02:14 PM
Part 2,

1) 50 - 20 = 30 answer is (a) taking right hand only + either hand

Answer 1 = betul

Tak yah bagi solution yer pasal senang jer. Kalau nak sila bagi tau.

Answer 2 = kira betul la ... heheheh ... jawapannya = cannot be determined

(10 + x)/2 divided by (10 + x) = 1/2
Cancel (10 + x), we get 1/2 = 1/2
Thus x cannot be determined.

Answer 3 = betul

Translate from words to Math :
Ja = 3A
A - 3 = Jo -1
E = 2A
So, Ja = 3A,
A = Jo + 2,
E = 2A

So, Ja > E > A > Jo

tahihidungmasin · Post time 13-3-2013 02:41 PM

PART 3

QUESTION 1
There are four people in a line. Sarah is between Barry and Mary. Mary is in front of two other people, and John is directly in front of Mary.
Who is first in line, second, third, and fourth?

QUESTION 2
If A = 250 percent of B, what percent of A is B?
(a) 1/250 percent
(b) 25 percent
(c) 40 percent
(d) 50 percent
(e) 125 percent

QUESTION 3
What is the next letter in the following series : y z v w s t p q?