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You are not logged in. #326 20090129 01:34:22
Re: Brain Teasers#234. Let S be a set of positive integers such that every elemnt n of S satisfies the conditions (ii) every digit in n is odd. How many elements of S are divisible by 3? #235. A string of three English letters is formed as per the following rules: (a) The first letter is any vowel. (b) The second letter is m, n, or p. (c) If the second letter is m, then the third letter is any vowel which is different from the first letter. (d) If the second letter is n, the third letter is e or u. (e) If the second letter is p, then the third letter is the same as the first letter. Question(I) : How many strings of letters can possibly be formed using the above rules? Question (II) : How many strings of letters can possibly be formed using the above rules such that the third letter of the string is e? Character is who you are when no one is looking. #327 20090129 01:36:24#328 20090129 01:39:05
Re: Brain Teasers#236. Stephen and Martin run a race between two points A and B 5 kilometers apart. Stephen starts at 9 am at a speed of 5 km/hour, reaches B, and returns to A at the same speed. Martin starts at 9.45 am from A at a speed of 10 km/hour, reaches B and returns to A at the same speed. Character is who you are when no one is looking. #329 20090129 01:50:29
Re: Brain TeasersAnswers to #232 and #233: Character is who you are when no one is looking. #330 20090129 03:47:31
Re: Brain TeasersI would much appreciate it if you could state your question carefully. “How much faster than” does not sound to me like asking for a ratio. #331 20090129 11:53:54#332 20090130 02:33:06
Re: Brain TeasersAnswers to #234, #235, #236: Character is who you are when no one is looking. #333 20090130 02:55:55
Re: Brain Teasers#237. What is the sum of all the 4 digit numbers that can be formed by using the digits 2, 4, 6, and 8 if repetition is not allowed? Character is who you are when no one is looking. #334 20090131 02:37:02
Re: Brain Teasers#240. P, Q, S, and R are points on the circumference of a circle of radis r, such that PQR is an equilateral triangle and PS is a diameter of the circle. What is the perimter of the quadrilateral PQSR? Character is who you are when no one is looking. #335 20090131 07:34:45#336 20090131 16:45:45
Re: Brain TeasersAnswers to #237, #240, #241, and #242: Character is who you are when no one is looking. #337 20090131 17:46:39
Re: Brain Teasers#243. The digit on the extreme right immediately before the zeros in #244. Consider a traingle with vertices (41,0), (0,41), and (0,0) in the Cartesian plane. What is the number of points with integer coordinates inside the triangle excluding all points on the boundary? Character is who you are when no one is looking. #338 20090131 22:02:57#339 20090131 23:25:47
Re: Brain TeasersThat was a good attempt. Character is who you are when no one is looking. #340 20090131 23:37:34
Re: Brain Teasers#245. A milkman mixes 20 liters of water with 80 liters of milk. After selling onefourth of this mixture, he adds water to replenish the quantity that he has sold. What is the proportion of water to milk after the addition of water the second time? Character is who you are when no one is looking. #341 20090131 23:54:53#342 20090201 00:04:43
Re: Brain TeasersAnswers to #245, and #246: Character is who you are when no one is looking. #343 20090201 00:37:48
Re: Brain Teasers#248. If a man rides a bicycle at 10 km/hour, then he arrives at a certain place at 1 p.m. If he rides the bicycle at 15 km/hour, he reaches at 11 a.m. At what speed must he ride to get there at noon? Character is who you are when no one is looking. #344 20090201 01:50:25
Re: Brain Teasers#251. Assume that an equal number of people are born on each day. Find the percentage (to three places after the decimal) of people whose birthday would fall on February 29? Character is who you are when no one is looking. #345 20090201 18:17:54
Re: Brain Teasers#253. A young girl counted in the following manner with the fingers on her left hand. She started by calling the thumb 1, the index finger 2, the middle finger 3, the ring finger 4, and the little finger 5; then reversed the direction, calling the ring finger 6, the middle finger 7, the index finger 8, the thumb 9, then back to the index finger for 10, middle finger for 11 and so on. She counted up to 1994. In which finger did she end? What would be the sum of all the elements of the subset ? Last edited by ganesh (20090202 00:01:01) Character is who you are when no one is looking. #346 20090201 23:52:10
Re: Brain TeasersLast edited by JaneFairfax (20090202 00:14:36) #347 20090202 00:03:53
Re: Brain TeasersAnswer to #253: Character is who you are when no one is looking. #348 20090202 00:18:00#349 20090202 00:36:55
Re: Brain TeasersAnswer to #254: Character is who you are when no one is looking. #350 20090202 00:54:31
Re: Brain Teasers#255. If you use \dfrac instead of just \frac, you can make it look better. And use \ldots for three baseline dots (called an ellipsis). 