# Equity trader Interview Questions

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Equity Trader interview questions shared by candidates### If you have 9 marbles and one is heavier than the other 8. How can you use only a balance beam to figure out which is the heavy one if you can only use it twice.

6 Answers↳

@qq11, I don't think your answer is right either. The question specifically says the balance beam can only be used twice, so I assume the question is asking how to find the heaviest marble by using the beam twice, not 3 times. You simply just split the 9 marbles into groups of 3. Put two sets on each side of the balance beam, and this will tell you which set has the heavy marble. After that, just take the heavy set of 3 marbles and put 2 of them on the balance beam, and you'll know which marble is the heavy marble. Less

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Ooo and ooo and ooo. First try: Ooo vs ooo => Ooo is heavier. Now take two of those and put one on each scale. If equal than the third is heaviest. If not equal, heavier one is heaviest. OR try ooo vs. ooo. Equal. Repeat step two for the pile that is established to be Ooo. Less

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@qq : go kill yourself.....are you really thinking about sayng to put the marble in your hand?? c mon bro.......alex is right btw Less

### If the clock is at 9:30, what angle is it at?

5 Answers↳

Isn't it 90 + 15 = 105 degrees?

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Yea its 105 degrees

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It's 90 degrees between 9 and 6 o'clock but the hour hand will move half way towards 10. Since there's 3 hours between the 9 and 6 we can say 1 hour = 90/3 = 30. The initial 90 degrees + the additional (1/2)*30 = 105 degrees. Less

### How many times will you write 'nine' if you wrote out the numbers 1 to 100?

5 Answers↳

20

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correction to the above, if you're writing the numbers with letters as opposed to numerically the correct answer is 10. Less

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9,29,39,49,59,69,79,89,99...19 isn't one..so 9

### Given two die, what is the probability that the sum when rolled would add up to six?

4 Answers↳

5/36

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5/36 is right.... Combinations that add up to six: 1 and 5, 2 and 4, 3 and 3, 4 and 2, 5 and 1. So we have 5 successes. There are 36 individual outcomes because there are 6 sides on each die and 6*6 = 36 So we have 5/36. Less

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1/6

### You have 25 horses and can race 5 of them at a time. What is the minimum number of races required in order to find the three fastest horses?

4 Answers↳

Answer is 7, the solution can be found online as this is somewhat common in interviews. Less

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Wouldnt it be 5 races? just time each of them

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Wouldn't it be 6? 5 inital races, then you take the winners of each race and race them once more Less

### 100 pennies in a jar. 1 penny has 'heads' on both sides. You pick a penny out of the jar and give it to your friend (without looking at the penny). Your friend flips the penny in the air and gets 7 heads in a row. Which penny do you have? Why?

3 Answers↳

Chance of 1 Heads = .5 Chance of 7 heads in a row = (.5)^7 to do this in your head think of fractions... (1/2)^7 = (1/2*1/2=1/4, * 1/2=1/8, * 1/2 = 1/16....if you do it seven times you get 1/128. so you have a better chance to pick out the penny with two heads (1/100) than to get 7 heads in a row (1/128) Less

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99 times out of 100 you take the normal penny. prob that normal penny give 7 heads in a row is 1/128. so, prob that he has special penny is 1/100 / (1/100 + 0.99*1/128) = 56.2% Less

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~56.4% that you have the 2-headed penny.

### You're a casino introducing a new game. The games rules: Playing cards numbered 1 through 10 lay face down on a table, the customer picks a card and whatever number it is he/she wins that dollar value. Ex. I flip a 2 over, I win 2 dollars. Question: How much do we charge for the game? Why?

2 Answers↳

1+2+3+4+5+6+7+8+9+10=55 55/10 = 5.5 = Average Expected Winning Price it higher then that number to be profitable Less

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Whatever will maximize the value from your customers.

### what is the angle between hour and minute hand at 10:30 how to escape a room without windows how much dust in a hole of 10*12*10 inches indexes and bond interest rates of prior day behavioral questions: who would you like to invite for dinner

2 Answers↳

should be 135

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Angle Problem: The hour hand is halfway between the 10 and 11 and the minute hand is on the 6, so they are 4.5 away and there are 12 total on the clock. 4.5/12 * 360 = 30*4.5 = 45*3 = 135 degrees Less