Math Challenges

Submissions for Problem #2

Problem #2

The monkeys at the zoo have discovered that the ACME brand monkey-feeder is malfunctioning. It's giving out different quantities depending on how many animals have already used it.

The first monkey received two bananas, while the second monkey received five, and the third monkey received eight bananas. If it keeps on going at this rate, how many bananas will the 21st monkey receive?

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fish-face

Solution: \( 62 \)

Explanation:
Arithmetic progression with first term 2 and common difference 3. Formula is a_n = a_1 + (n-1)d.

zapwai

Solution: \( 62 \)

Explanation:
The sequence is multiples of 3, beginning at / shifted by 2. For the (n+1)st monkey we have a formula, 2 + 3n. We can imagine a map, n -> # of bananas 0 -> 2 (0 is the first monkey) 1 -> 5 2 -> 8 in this way the 21st monkey will be n = 20, and we should get 20 -> 2 + 3(20) = 62 62 bananas!