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Mamma: "Let me think, Tommy. Well, our three ages add up to exactly seventy years."

Tommy: "That's a lot, isn't it? And how old are you, Papa?"

Papa: "Just six times as old as you, my son."

Tommy: "Shall I ever be half as old as you, Papa?"

Papa: "Yes, Tommy; and when that happens our three ages will add up to exactly twice as much as to-day."

Tommy: "And supposing I was born before you, Papa; and supposing Mamma had forgot all about it, and hadn't been at home when I came; and supposing..."

Mamma: "Supposing, Tommy, we talk about bed. Come along, darling. You'll have a headache."

Now, if Tommy had been some years older he might have calculated the exact ages of his parents from the information they had given him. Can you find out the exact age of Mamma?

[Ref: ZPYU] Mamma's Age. Amusements In Mathematics by Henry Ernest Dudeney (1917).

Hint: The answer involves years and months.

Answer: The age of Mamma must have been 29 years 2 months.

That of Papa, 35 years; and that of the child, Tommy, 5 years 10 months. Added together, these make seventy years. The father is six times the age of the son, and, after 23 years 4 months have elapsed, their united ages will amount to 140 years, and Tommy will be just half the age of his father.

The answer above is taken from the original book, here is another version of the answer:

If we call Tommy T, Mamma M and Papa P we can see that:

"our three ages add up to exactly seventy years" leads to

T + M + P = 70 (1)

"Just six times as old as you" leads to

P = 6 x T (2)

In an unknown number of years (Y) "Shall I ever be half as old as you" leads to:

P + Y = 2 x (T + Y) (3)

and "our three ages will add up to exactly twice as much as to-day" leads to:

(T + Y) + (M + Y) + (P + Y) = 140

which can be written as

T + M + P + 3Y = 140 (4)

We can see from (4) and (1) that

3Y = 70

so

Y = 70 ÷ 3 (5)

Using (2) and (5) in (3) we have

P + Y = 2 x (T + Y)

6 x T + 70÷3 = 2 x (T + 70÷3)

4 x T = 70÷3

T = 70÷12 (6)

We can now use (6) in (2) to see that:

P = 6 x T

P = 6 x 70÷12

P = 70÷2

And using the values for T and P in (1) we have:

T + M + P = 70
70÷12 + M + 70÷2 = 70

Multiply throughout by 12 to give:

70 + 12 x M + 420 = 840

12 x M = 840 - 420 - 70

12 x M = 350

M = 350÷12

So: Tommy = 70÷12 = 5.83333 = 5 years 10 months.
Papa = 70÷2 = 35 = 35 years.
Mamma = 350÷12 = 29.1666 = 29 years 2 months.

QED.

Puzzle 417

During the recent BrainBashers cipher convention, a Morse code contest took place. The contest consisted of a Morse code transmission where the spaces between the letters and words were missing. Can you decipher the sequence and find the well known proverb?

Aliens landed in downtown Chicago last night. Most locals stepped outside to see the space-ship's massive wingspan. Amazingly, seven people failed to see the sight before them, as they took shelter from the bright light that shone from above.

Aliens landed in downtown Chicago last night. Most locals stepped outside to see the space-ship's massive wingspan. Amazingly, seven people failed to see the sight before them, as they took shelter from the bright light that shone from above.

Puzzle 419

What is half of two plus two?

[Ref: ZHVM]

Hint: There are two possible answers.

Answer:
Either 2 or 3 depending on whether the initial two is halved first.

"half of two" plus two

or

half of "two plus two"

The normal rules of BIDMAS/BODMAS do not apply to this question as this is not a mathematical expression, i.e. it is a written as an English question, and not a well-formed Mathematics question.

Puzzle 420

Using the BrainTracker grid below, how many words can you find? Each word must contain the central M and no letter can be used twice. The letters do not have to be connected. Proper nouns are not allowed, however, plurals are. Can you find the nine letter word?

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