Time and Work method Tips

Important Facts: 1.If A can do a piece of work in n days, then A’s 1 day work=1/n 2.If A’s 1 day’s work=1/n, then A can finish the work in n days.Ex: If A can do a piece of work in 4 days,then A’s 1 day’s work=1/4. If A’s 1 day’s work=1/5, then A can finish the work in 5 days 3.If A is thrice as good workman as B,then: Ratio of work done byA and B =3:1. Ratio of time taken by A and B to finish a work=1:34.Definition of Variation: The change in two different variablesfollow some definite rule. It said that the two variables varydirectly or inversely.Its notation is X/Y=k, where k is calledconstant. This variation is called direct variation. XY=k. Thisvariation is called inverse variation.5.Some Pairs of Variables: i)Number of workers and their wages. If the number of workers increases, their...

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Find thevalue of X?

What is the value of the variable X in the equation as shown in the figu...

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Divide by Parts

Divide 110 into two parts so that one will be 150 percent of the other. What are the 2 numbe...

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Is A Guilty?

There was a robbery in which a lot of goods were stolen. The robber(s) left in a truck. It is known that : (1) Nobody else could have been involved other than A, B and C. (2) C never commits a crime without A's participation. (3) B does not know how to drive. So, is A innocent or guil...

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Who is in the picture?

Stephen was looking at a photo. Someone asked him, "Whose picture are you looking at?" He replied: "I don't have any brother or sister, but this man's father is my father's son." So, whose picture was Stephen looking ...

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Order Finder

Isaac and Albert were excitedly describing the result of the Third Annual International Science Fair Extravaganza in Sweden. There were three contestants, Louis, Rene, and Johannes. Isaac reported that Louis won the fair, while Rene came in second. Albert, on the other hand, reported that Johannes won the fair, while Louis came in second. In fact, neither Isaac nor Albert had given a correct report of the results of the science fair. Each of them had given one correct statement and one false statement. What was the actual placing of the three contestan...

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Bulbs

There are three switches downstairs. Each corresponds to one of the three light bulbs in the attic. You can turn the switches on and off and leave them in any position. How would you identify which switch corresponds to which light bulb, if you are only allowed one trip upstairs?...

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Immortal wars

the war is legend and myth it was started in temples the three opposing leaders were siblings by magic blood one ruled the ocean other the sky last the dead they were in times of ancient each wants the throne what and who are the three opposing leaders and what throne are they fighting over?...

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The 11 Rule

You likely all know the 10 rule (to multiply by 10, just add a 0 behind the number) but do you know the 11 rule? It is as easy! You should be able to do this one in you head for any two digit number. Practice it on paper first!To multiply any two digit number by 11: For this example we will use 54. Separate the two digits in you mind (5__4). Notice the hole between them! Add the 5 and the 4 together (5+4=9) Put the resulting 9 in the hole 594. That's it! 11 x 54=594 The only thing tricky to remember is that if the result of the addition is greater than 9, you only put the "ones" digit in the hole and carry the "tens" digit from the addition. For example 11 x 57 ... 5__7 ... 5+7=12 ... put the 2 in the hole and add the 1 from the 12 to the 5 in to get 6 for a result of 627...

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Squaring a 2-digit number ending in 8

Choose a 2-digit number ending in 8. The last digit of the answer is always 4: _ _ _ 4 Multiply the first digit by 6 and add 6 (keep the carry): _ _ X _ Multiply the first digit by the next consecutive number and add the carry: the product is the first two digits: XX _ _. Example: If the number is 78: The last digit of the answer is 4: _ _ _ 4 Multiply the first digit (7) by 6 and add 6 (keep the carry): 7 × 6 = 42, 42 + 6 = 48; the next digit of the answer is 8 (keep carry 4): _ _ 8 4 Multiply the first digit (7) by the next number (8) and add the carry (4): 7 × 8 = 56, 56 + 4 = 60 (the first two digits): 6 0 _ _ So 78 × 78 = 6084. See the pattern? For 38 × 38 The last digit of the answer is 4: _ _ _ 4 Multiply...

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Squaring a 2-digit number ending in 7

Choose a 2-digit number ending in 7. The last digit of the answer is always 9: _ _ _ 9 Multiply the first digit by 4 and add 4 (keep the carry): _ _ X _ Multiply the first digit by the next consecutive number and add the carry: the product is the first two digits: XX _ _. Example: If the number is 47: The last digit of the answer is 9: _ _ _ 9 Multiply the first digit (4) by 4 and add 4 (keep the carry): 4 × 4 = 16, 16 + 4 = 20; the next digit of the answer is 0 (keep carry 2): _ _ 0 9 Multiply the first digit (4) by the next number (5) and add the carry (2): 4 × 5 = 20, 20 + 2 = 22 (the first two digits): 2 2 _ _ So 47 × 47 = 2209. See the pattern? For 67 × 67 The last digit of the answer is 9: _ _ _ 9 Multiply...

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Squaring a 2-digit number ending in 6

Choose a 2-digit number ending in 6. Square the second digit (keep the carry): the last digit of the answer is always 6: _ _ _ 6 Multiply the first digit by 2 and add the carry (keep the carry): _ _ X _ Multiply the first digit by the next consecutive number and add the carry: the product is the first two digits: XX _ _. Example: If the number is 46, square the second digit : 6 × 6 = 36; the last digit of the answer is 6 (keep carry 3): _ _ _ 6 Multiply the first digit (4) by 2 and add the carry (keep the carry): 2 × 4 = 8, 8 + 3 = 11; the next digit of the answer is 1: _ _ 1 6 Multiply the first digit (4) by the next number (5) and add the carry: 4 × 5 = 20, 20 + 1 = 21 (the first two digits): 2 1 _ _ So 46 × 46 = 2116. ...

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