Hi!
Why is this blog still so stagnant? It's the holidays! Everyone should have plenty of time to post on the blog... Anyway, I'm so excited about 9th June! (It's the class outing in case you forgot) Hope everyone's enjoying their much-deserved break! :)
Oh yes, I've decided to give everyone a week's period to think through the "Very Hard" puzzles. Hence, from now on, after every "Very Hard" puzzle, I will only post another puzzle a week later, so you all can have enough time to ponder and solve the puzzle.
Okay, here's Puzzle 15!
LATE
Difficulty: Medium
Disclaimer: Any similarities to actual events in this puzzle are purely coincidental.
One day, Mr. Lim was driving from home to school. He estimated that he would have to drive at an average speed of 40km/h if he were to arrive in school on time.
For some unknown reason, his car only drove at an average speed of 20km/h during the first half of his journey.
What must the speed of Mr. Lim's car be for the second half of the journey in order to arrive in school on time?
This puzzle may be short, but it might not be sweet...
While you ponder over the puzzle, here's the answer the 3rd "Very Hard" Puzzle 14! Drag your mouse over the empty space below to reveal the answer.
Wow... Puzzle 14 was quite a hard puzzle... O.O
The answer is 134! Look below for the long explanation...
What is the only number on the faces of the dice, which however flipped, looks the same? 96! Hence, you can use 96 to identify the 2 different dice.
The die on the left in the first figure and the die on the right in the last figure are the same (We'll call it Die 1)! Also, the die on the right in the 1st figure and the die on the left in the last figure are the same (We'll call it Die 2), but notice that even though two of their faces appear similar, the other numbers don't match! So they are actually opposite views of each other! You should have something like this...
You have the full net of Die 2! Now, you know the no. underneath Die 2 in the 1st figure is 16/91, and the no. in the last figure is 68/89. Although you can't tell which is which no. in the latter, but you can in the former!
152 - 16 = 136 (X)
152 - 91 = 61 :)
Thus, the no. underneath Die 2 in the 1st figure is 91, and the no. underneath Die 1 is 61!
Now, try to match the net of Die 2 (the one above) to one of the dice in the 2nd figure.
You'll find that it matches to the die on the left, so the die on the right must be Die 1! However, when you try to match the die on the right to the net of Die 1, you'll find that there are 2 possible nets for Die 1... We'll just have to test them out one by one...
1st possibilty
BUT...
In this possibility, the no. underneath Die 1 in the 1st figure will be 66/99, NOT 61!
Hence, this is not possible.
That leaves the 2nd possibilty for the correct complete net of Die 1:
Now we have the nets, but we don't have the values of the no.s!
We'll just have to figure them out one by one...
Remember? Underneath the 2 dice in the 1st figure is 61 (Die 1) and 91 (Die 2).
So, we have this...
The underline shows which way up the no.s should be.
Other than differenciating 61 and 91, it can also differenciate 19 too, since all no.s are different, and 19 looks like 61 when flipped around.
Using this method we can differenciate most of the no.s!
Now, let's look at the no.s underneath the dice in the 2nd figure.
They are: 68/89 (Die 1) and 66/99 (Die 2).
Only 89 and 99 add up to 188, so here's what you should have...

Now, let's try to get the answer...
As we already know, in the last figure, Die 1 is on the right and Die 2 is on the left.
Underneath Die 1 is 66. Underneath Die 2 is 68.
Hence, when added together they give an answer of... 134!
I KNOW... it's super long and complicated, I don't blame you for not getting it the first time. You can e-mail me if you need any clarification.
P.S. The two possibilities of the net for Die 1 was an unexpected error. I didn't notice it until I was typing out the answer. Luckily, it didn't turn out to be a major error. :)
:)
Glen