MedVision ad

MATHS MARATHON! (Mathsathon?) (1 Viewer)

addikaye03

The A-Team
Joined
Nov 16, 2006
Messages
1,267
Location
Albury-Wodonga, NSW
Gender
Male
HSC
2008
Bill is older than Ted by 9 years. If the digits in Bill's age is reversed, it gives Ted's age. The sum of their ages is 99. How old is Bill and Ted?

I just made this up then btw

EDIT:

Going to bed, heres the solution:

Ted's age: If we go 99-9 (sum - difference) then we get 90 now divide by 2= 45. Bill's age is therefore 54. Which has a difference of 9
 
Last edited:

iMAN2

Member
Joined
Mar 22, 2007
Messages
217
Gender
Male
HSC
N/A
A father is nine times the age of his son. In 5 years time, he will be four times the age of his son. How old are they now?

Father's age = F
Son's age = S

9S=F
F+5= 4 x (S+5)
F+5= 4S + 20
F= 4S + 15

Simulatenous Equations:

F= 4S + 15
9S = 4S + 15 (Substituting F=9S)
5S= 15
S= 5

9S=F
9 x 5 = 45
F=45

Son is 5, Father is 45.
 

Clank_

Member
Joined
May 8, 2009
Messages
272
Location
Quartu
Gender
Male
HSC
2011
When reading a page of his book, Jarrod declared, ‘There are twice as many
pages after this page than before this page’.
How many pages could this book contain?
Indicate whether each of the following is Correct or Incorrect.
a. 202 b. 303 c. 404 d. 505
 

addikaye03

The A-Team
Joined
Nov 16, 2006
Messages
1,267
Location
Albury-Wodonga, NSW
Gender
Male
HSC
2008
When reading a page of his book, Jarrod declared, ‘There are twice as many
pages after this page than before this page’.
How many pages could this book contain?
Indicate whether each of the following is Correct or Incorrect.
a. 202 b. 303 c. 404 d. 505
a)incorrect
b)correct
c)incorrect
d) correct

(nb: all the correct answers are odd)

This is because, let x be the page amount before that page, therefore 2x is the number of pages after the current page. The trick is not to include the page that he is currently on, so that's one extra page.

If a) 202 pages, then minus one page for the page hes currently on and we get 201, when 201/2 we do not get an integer, and pages are whole numbers.

If b) 303 pages, minus one that gives 302 and then 302/2=151 which is an integer.

Similar story for c) and d)

Hope this explanation helps
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top