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# KCC's Quizzes AQQ231 about Birthdays and Cake Candles

Mary celebrates her birthday every year from the very first year.

The number of candles on her cake used reflects her age : 1 at age of 1, 2 at age of 2, 3 at age of 3 etc…

Up to now, she has blow out a total of 946 candles.

Questions:

1. How old is Mary today?
2. In an other family, there are 2 sisters, Ann and Helen. Helen is 5 years younger than Ann. They both follows the same scenario for the candles as Mary. The cumulated candled used by the 2 sisters is 1687. How old are Ann and Helen?

P.S. If you think there are still colleagues or friends (internal or external) you think who can be interested in those quizzes, please let let them know....

Kuo-Chang

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[edited by: emassa at 1:54 PM (GMT -4) on 29 Mar 2023]
Parents
• 1 + 2 + 3 ... + n = n(n+1)/2  is the series.

1.   Mary has blown 946 candles.
n(n+1)/2 = 946
solving for n we get  n=86/2 = 43
Mary now is 43 years  old.

2.  If Ann is A years and Helen is A-5 years of age.
A(A+1)/2  +  [A-5](([A-5]+1)/2 = 1687

solving for A , we get.  A= 43 so H =43-5=38

Ann is 43 years of age  and Helen is 38 years of age.

• 1 + 2 + 3 ... + n = n(n+1)/2  is the series.

1.   Mary has blown 946 candles.
n(n+1)/2 = 946
solving for n we get  n=86/2 = 43
Mary now is 43 years  old.

2.  If Ann is A years and Helen is A-5 years of age.
A(A+1)/2  +  [A-5](([A-5]+1)/2 = 1687

solving for A , we get.  A= 43 so H =43-5=38

Ann is 43 years of age  and Helen is 38 years of age.

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