Compilation of all things math --- questions obtained via students' consultation, related math sites. * Do also check out my EduTech contributions at go.gov.sg/changcl
Friday, December 27, 2013
Saturday, November 30, 2013
P6 numbers (fr Keith Tan, heuristics: pattern, make-a-list)
A telephone number consists of 10 digits. If the third number must start with either a 9 or 8 and the numbers in the number cannot be used more than thrice, how many possible telephone number combinations can there be if the first two digits in the front of the last 8 numbers must not add up to 10?
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Warning! This is more complicated than meets the eye!
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Warning! This is more complicated than meets the eye!
Wednesday, November 27, 2013
P6 Geometry, clock (algebra, fr CCL)
Solve this extension to the earlier question:
(a) How many occasions are there when the minute hand and the hour hand coincide with each other?
(b) When are these occasions* ?
(c) What are the angles of both the hands clockwise from the position "12" at those instances where both hands coincide?
____
* Warning! Except for the first and most trivial case (1200) the other cases comprise weird fractions (with minutes expressed as mixed numbers) :)
__________
If you have done your due diligence to solve the problem, check your answers against mine:
click here.
(a) How many occasions are there when the minute hand and the hour hand coincide with each other?
(b) When are these occasions* ?
(c) What are the angles of both the hands clockwise from the position "12" at those instances where both hands coincide?
____
* Warning! Except for the first and most trivial case (1200) the other cases comprise weird fractions (with minutes expressed as mixed numbers) :)
__________
If you have done your due diligence to solve the problem, check your answers against mine:
click here.
Sunday, November 24, 2013
P6 geometry, time ("clock geometry" fr CCL)
What is the size of the acute angle between the minute hand and the hour hand for the following cases:
(a) 06 00
(b) 06 30
(c) 12 34
(d) 16 44
(e) 15 33
Give your answers in degrees, if applicable in mixed numbers in in the simplest form.
(a) 06 00
(b) 06 30
(c) 12 34
(d) 16 44
(e) 15 33
Give your answers in degrees, if applicable in mixed numbers in in the simplest form.
Thursday, November 7, 2013
Monday, November 4, 2013
Monday, October 28, 2013
Wednesday, October 23, 2013
Monday, October 21, 2013
Sunday, October 20, 2013
Friday, October 18, 2013
A question on age (fr
Jeremy is 11 years old. Jeremy's father is 6 times as old as Jeremy's sister. Jeremy's sister is 30 years younger than his father.l
a) how old is Jeremy's father?
b) how old will Jeremy be when his father is 65 years old?
a) how old is Jeremy's father?
b) how old will Jeremy be when his father is 65 years old?
Thursday, October 17, 2013
Friday, October 11, 2013
The Chipmunk and Acorns (fr Mr CCL)
Alvin, the chipmunk, is at the foot of a Supertree (See Point A). There are some acorns at the top of the Supertree (See Point B). How many ways are there for the chipmunk at Point A to reach the acorns at Point B?
Note: The chipmunk can only climb upwards and not downwards.
Note: The chipmunk can only climb upwards and not downwards.
Thursday, October 3, 2013
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