Brain Teasers and Puzzles 

Workings

Answer
Hydrogen.

Workings

Hint
Start by looking at the consonants and vowels (AEIOU).

Answer
65 tonnes.

Vowels (AEIOU) are worth 3 and consonants are worth 5, added together and then multiplied by the number of ingots.

So TIN has 1 vowel (worth 3) and 2 consonants (worth 10).

Added gives 13, then multiplied by 5 ingots = 65.

Workings

Hint
How much of a warren can each rabbit dig in one hour?

Answer
2 hours.

Reasoning
The small rabbit can dig a warren in nine hours, so digs ¹/₉ in one hour.

The medium rabbit can dig a warren in 6 hours, so digs ¹/₆ in one hour.

The large rabbit can dig a warren in four and a half hours, so digs ¹/_4.5 in one hour.

   1 Hour = ¹/₉ + ¹/₆ + ¹/_4.5

To make the denominators all the same, we can multiply through by ¹⁸/₁₈ to give:

   1 Hour = ²/₁₈ + ³/₁₈ + ⁴/₁₈

   1 Hour = ⁹/₁₈

   1 Hour = ¹/₂

So in one hour, they have dug half a warren, the whole warren will therefore take 2 hours.

Workings

Hint
Look at the number of letters in each name.

Answer
Yes.

Because there is an odd number of letters in the name.