I Used to Be The Light of Your Life

I used to be the light of your life,
I’d keep you warm while I cried,
Now I’m forgotten and tossed away.

What am I?

A candle. They used to be a primary source of light, and to a lesser extent heat. The “crying” is the wax rolling down the candle.

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Lying On Certain Days of the Week

Angel lies on Mondays, Tuesdays and Wednesdays but tells the truth the rest of the week.

Brenda lies on Thursdays, Fridays and Saturdays, but tells the truth every other day.

Angel says, “Yesterday I was lying.”

Brenda replies, “So was I.”

What day was it?

Thursday.

Putting the information in a table makes it easier to solve. We’ll use A for Angie, B for Brenda, T for truth and F (false) for lying.

  S M T W Th F S
A T F F F T T T
B T T T T F F F

To begin with, there aren’t any days where both of them told the truth and lied the day before, so we know one of them must be lying.

So we have two options, either Angel is lying or Brenda is.

Option 1. Angel is lying.

In order for this to be the case, she needs to be lying today and telling the truth yesterday, so we need two days in a row with T F. And if Brenda is telling the truth, she would need two days with F T. That means we’re looking for two days that have

Angie:  T F
Brenda: F T

Option 2. Brenda is lying.

This is just the reverse of the above, so we need to find:

Angie:  F T
Brenda: T F

The only day that matches either of the two options is Thursday, and it’s option 2. Brenda is the liar.

Posted in Brain Teasers

Move Your Digits

By moving one of the following digits, make the equation correct.

62 – 63 = 1

26 – 63 = 1
(26 = 2x2x2x2x2x2 = 64, ∴ 64 – 63 = 1)

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Break, Light, May

What word can be added before or after these words to make a new word or phrase?

Break, Light, May

Day. Daybreak, daylight, may day.

Posted in Riddles

Hot My Entire Life

I have been hot my entire life. Put me in water or in a freezer for days and I will still be hot. My red color should tell you but don’t be deceived, even when I’m green, I’m still hot. What am I?

A red or green laser. Red and green pepper also works.

Technically, the laser beam itself isn’t hot, but lasers can heat up what they’re shining on.

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Mixed Animals for $100

At the market you can buy a cow for $10, a pig for $1 and 8 hens for $1. How many animals would you need to buy to get 100 mixed animals for exactly $100?

7 cows, 21 pigs and 72 hens. The trick to this is finding the combination of cows and hens with the same cost and quantity since pigs are already equal. The magic combination is 7 cows and 72 hens, giving you 79 animals that cost $79 ($70 + $9). Then you just add 21 pigs to get to 100 animals.

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Soldiers Line Up Spaced With Pride

Soldiers line up, spaced with pride,
Two long rows lined side by side,
One sole unit can decide,
If the rows will unite or divide.

What am I?

A zipper.

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Money For Answers

A dad offered to pay his son $5 for every correct answer on his math test. His son said he would pay his Dad $8 for every incorrect answer. There were 26 questions on the test and no money was exchanged.

How did this happen?

The son got 16 questions correct and missed 10. This means he owed his Dad 10 * $8 = $80, but his Dad owed him 16 * $5 = $80, so it was a wash.
Two math equations to solve it are x + y = 26 and 5x = 8y.

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What Letter Comes Next?

The letters in this series are ones that don’t begin something. Figure out what that something is, and what letter comes next.

B E J ?

Q. The thing they don’t begin is states in the United States of America. The final three letters in the series are X, Y and Z.

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False Positive HIV Test

Imagine an HIV test that is 95% accurate (false positive rate of 5%) and around 2% of the tested population is infected with HIV. What is the probability that you actually have HIV when your test comes back positive?

29%

To read more about this, see the False Positive Paradox page on Wikipedia.

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