Brain Teasers

Jai Ganesh · 2008-12-28 02:05:02

#86. Find the value of

.

careless25 · 2008-12-28 15:56:38

i feel like these were 2 easy for me ganesh. I like patterns and like to solve them, if you have more pls post.

careless25 · 2008-12-28 16:03:32

Jai Ganesh · 2008-12-28 16:27:51

Answers to #79 and #81, #82, #83, #84, and #85.
Answer to #81 is correct, Answers to #82, #83, #84, and #85 are all correct.
Please check your answer to #79 again!

Your performance......

As required by you in post #177, I shall post more of these soon

Jai Ganesh · 2008-12-29 01:32:15

careless25, these questions are posted based on your post #177:-

Find the wrong number in the series in the series of numbers given below:-

#87. 6, 12, 30, 84, 248, 732

#88. 4, 6, 24, 48, 144, 288

#89. 3, 8, 18, 36, 73, 148

#90. 1, 2, 6, 12, 36, 70, 216

#91. 10240, 2560, 640, 140, 40, 10

#92. 2, 9, 45, 303, 1815, 10887, 65319

#93. 5, 10, 47, 136, 680, 2026, 10127

#94. 30, 90, 180, 540, 1080, 2160, 6480

#95. 3, 9, 23, 51, 115, 241, 495

#96. 625, 275, 375, 75, 225, 45, 135

#97. 12, 13, 18, 20, 24, 28, 30

#98. 57, 70, 84, 97, 110, 124, 138

#99. 32, 34, 48, 52, 64, 68, 80

#100. 720, 120, 24, 8, 2, 1, 1

#101. 5, 27, 61, 122, 213, 340, 509

Jai Ganesh · 2008-12-29 02:26:21

#102. Three pipes A, B, and C can fill a tank in 12, 15, and 20 hours respectively. If A is open all the time and B and C are open for one hour each alternately, in what time would the tank be full?

Jai Ganesh · 2008-12-29 16:51:39

#103. Out of five questions in a question paper, one-twentieth of the students answer all the questions, and one-twentieth of them answer none. Of the rest, one-fourth answer four questions and one-fifth answered one question only. If 24½ % of the total number of students answered three question, what is the total number of students who appeared for the test?

Jai Ganesh · 2008-12-29 18:39:13

Complete the series:-

#104. 16, 33, 65, 131, 261, ____

#105. 2, 6, 12, 20, 30, 42, 56, ____

#106. 8, 24, 12, 36, 18, 54, ____

#107. 2, 5, 9, 19, 37, ____

#108. 2197, 1331, 343, 125, 27, ____

careless25 · 2008-12-30 04:43:08

A bit more challenging!!
Thats it for now, i will solve more later.

Thx again,
C25

Jai Ganesh · 2008-12-30 18:28:06

Answers to #87, #88, #89, #90, #91, and #92:-
All answers other than #90 correct. That is five out of six correct.
Regarding #90,
#90. 1, 2, 6, 12, 36, 70, 216
The pattern is 1st number multiplied by 2, the second number multiplied by 3, the third number multiplied by 2, the fourth number multiplied by 3 and so on. Hence, 70 is the wrong number in the series.
Your performance has been excellent.

Jai Ganesh · 2008-12-30 19:25:04

Complete the series:-

#109. 16, 13, 17, 12, 18, 11, ___.

#110. 3, 10, 29, 66, 127, ____.

#111. 1, 5, 13, 25, 41, _____.

#112. 99, 98, 94, 85, 69, 44, ____.

#113. 49, 51, 54, 27, 9, 11, 14, ____.

#114.

.

#115. 6.75, 4.5, 3, ____.

Jai Ganesh · 2008-12-31 23:04:55

#116. Complete the series:
1, 4, 14, 45, 139, 422, _____.

#117. Complete the series:
5, 9, 16, 29, 54, 103, _____.

#118. In a division, the divisor is ten times the quotient and five times the remainder. if the remainder is 46, determine the dividend.

#119. Find the least number which on being divided by 5, 6, 8, 9, and 12 leaves a remainder of 1 in each case but leaves no remainder when divided by 13?

#120. Four natural numbers, when added three at a time give the sums of 180, 197, 208 and 222. Find the numbers.

Jai Ganesh · 2009-01-01 03:13:55

#121. A contractor undertakes to do a certain job in 45 days and employs 15 persons for it. At the end of 36 days, he realizes the work is only half done. How many extra persons should he now employ to finish the work in time?

JaneFairfax · 2009-01-01 04:14:11

Jai Ganesh · 2009-01-01 17:02:03

Answer to #121:
You are perfectly right, Janefairfax!

Jai Ganesh · 2009-01-01 17:14:45

#122. The distance between two places X and Y is 60 kilometers. Two persons A and B start from X towards Y at the same time. The speed of B is 4 kilometers per hour less than that of A. A reaches Y, returns at once and meets B at a distance of 12 kilometers from Y. What is the speed of B?

Jai Ganesh · 2009-01-01 18:30:59

#123. A wrist-watch is sold at a profit of 20%. If both the cost price and the selling price are were decreased by $100, the profit would have been 5% more. What is the original cost price of the watch?

Jai Ganesh · 2009-01-02 02:36:54

#124. If the sum of two numbers be multiplied by each separately, the products obtained are 2418 and 3666. What are the numbers?

Jai Ganesh · 2009-01-02 02:49:20

#125. What is the value of

if
?

Jai Ganesh · 2009-01-02 16:49:11

#126. A solid is in the form of a right circular cylinder with hemispherical ends. the total height of the solid is 70 centimeters. The diameter of the cylinder is one-fourth its height. Find the volume of the solid.

#127. To do a certain piece of work, B takes four times as long as A and C together and C takes three times as long as A and B together. if all of them working together complete the work in 12 days, how long would C alone take to do the work?

#128. 3 glasses A, B, and C whose capacities are in the ratio 1:2:3 respectively are mixtures of acid and water. The ratios of acid to water in A, B, and C are 1:5, 3:5, and 5:7 respectively. The contents of these glasses are emptied into a single vessel. What is the ratio of acid to water in the vessel?

#129. Water flows at the rate of 10 meters per minute through a cylindrical pipe whose internal radius is 0.5 centimeter. How long would it take to fill a conical vessel whose radius at the top is 20 centimeters and depth is 21 centimeters?

#130. The average score of girls in a Mathematics test is 73 and that of the boys is 71. The average score of both boys and girls together is 71.8. Find the percentages of the number of girls and the number of boys who appeared in the test.

JaneFairfax · 2009-01-03 02:09:36

Jai Ganesh · 2009-01-03 02:29:35

Answer to #125:-
Correct again, JaneFairfax!!!

JaneFairfax · 2009-01-03 10:21:31

Jai Ganesh · 2009-01-03 17:29:24

Answer to #122:-
Perfectly right, Janefairfax!

Jai Ganesh · 2009-01-03 17:45:16

#131. What is the value of of

where
?

#132. 8 + 88 + 888 + 8888 + 88888 + ........ n terms = ?

Math Is Fun Forum

#176 2008-12-28 02:05:02

Re: Brain Teasers

#177 2008-12-28 15:56:38

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#178 2008-12-28 16:03:32

Re: Brain Teasers

#179 2008-12-28 16:27:51

Re: Brain Teasers

#180 2008-12-29 01:32:15

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#181 2008-12-29 02:26:21

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#182 2008-12-29 16:51:39

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#183 2008-12-29 18:39:13

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#184 2008-12-30 04:43:08

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#185 2008-12-30 18:28:06

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#186 2008-12-30 19:25:04

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#187 2008-12-31 23:04:55

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#188 2009-01-01 03:13:55

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#189 2009-01-01 04:14:11

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#190 2009-01-01 17:02:03

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#191 2009-01-01 17:14:45

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#192 2009-01-01 18:30:59

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#193 2009-01-02 02:36:54

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#194 2009-01-02 02:49:20

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#195 2009-01-02 16:49:11

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#196 2009-01-03 02:09:36

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#197 2009-01-03 02:29:35

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#198 2009-01-03 10:21:31

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#199 2009-01-03 17:29:24

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#200 2009-01-03 17:45:16

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