We have been quite lucky with the weather recently, it has got steadily warmer each day, over the last five days.
By this, I mean that the temperature rose by the same amount each day.
The average temperature was 2 °C and I know it froze on two occasions.
I also know the product of the temperatures was over 500 but below 2,000 and each temperature was an integer.
What were the last 5 temperatures?
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Hint
What must the middle temperature be?
Answer
The temperatures were -6, -2, 2, 6, 10 °C.
Each day increased by a steady 4 degrees.
As the temperature rose steadily each day and the average was 2 degrees, we know the middle temperature was 2 degrees.
If we assume a daily increase of 1, the sequence would be 0, 1, 2, 3, 4. This doesn't work we require 2 negative temperatures.
If we assume a daily increase of 2, the sequence would be -2, 0, 2, 4, 6. This doesn't work we require 2 negative temperatures.
If we assume a daily increase of 3, the sequence would be -4, -1, 2, 5, 8. This doesn't work as the product is less than 500.
If we assume a daily increase of 4, the sequence would be -6, -2, 2, 6, 10. This matches all of the requirements.
If we assume a daily increase of 5, the sequence would be -8, -3, 2, 7, 12. This doesn't work as the product is more than 2000.
So the only possible answer is -6, -2, 2, 6, 10.
