Easy Maths For Everyone

MATHEMATICS AFTERSCHOOOL Centre for social entrepreneurship, bikaner www.afterschoool.tk www.afterschool.tk

What will be the value of 1000 Rs. Invested every year after 3 years, interest rate 10 compounding annually.

• Rs. 1331 approx.

20 persons can do a work in 7 days, the number of persons required for completing the work in 28 days will be?

• 20 *7/28 = 5 persons will be required.

120 persons had provision for 200 days, after 5 days, 30 left, the remaining provision will last for how many days? • Step 1: total provision: 120*200 =24000 • Step 2: provision finished :120*5= 600 • Step 3: provision left: = 23400 • Step 4: Calculate days: 23400/90 = 260 days.

A garrison of 750 men has provision for 20 weeks, if at the end of 4 weeks, they are reinforced by 450 men, how long the provision will last?

• • • • •

Total food: 750*20 = 15000 Food consumed: 750*4 = 3000 Remaining provision: 12000 No. of men now: 1200 No. of days left: 12000/1200 = 10 weeks.

4/5th of the cistern is filled in 1 minute, how much more time will be required to fill the rest? • Step 1: four shares of cistern took 60 seconds – so one share will take – 60 /4 = 15 • Remaining is one share – so it will take 15 seconds.

5 AC use 6 units of energy running 9 hours a day, how much energy will be required by 8 new AC, which will run 10 hours a day (4 new ACs consume as much as 3 old ACs).

• • Take existing energy consumption, multiply by relative values – more the hours, more will be consumption so higher values should be numerator – so on. • 6 * (10/9) *(8/5) * (3/4) = 8 units

15 skilled men take 21 days of 8 hours each to do a work. How many days of 6 hours will be required by 21 unskilled men. 3 unskilled men do as much as 2 skilled men.

• 21 * (8/6) * (15/21) *(3/2) = 30 Ans.

15 men can build a wall 108 m long in 6 days, what length of similar wall can be built by 25 men in 3 days. • 108 * (25/15) * (3/6) = 90 Ans.

By selling an article for Rs. 110, a man looses 12%, for how much should he sell to gain 8%?

• Let us assume the cost = 100, currently selling at 88 – now we want to sell at 108 – so the equation is ready: • 110 * (108/88) = 135

By selling 100 pencils, a shopkeeper gains the selling price of 20 pencils, find his margin in %?

• Let us assume – one pencil sells at 1, total selling price = 100, profit = 20, cost = 80 • So margin: (20/80)*100 (remember to put cost as denominator) = 25%

There are two expenses – one fixed and one variable – when production is 200, the total cost is 1300, when production is 250, cost is 1600, what will be total cost at 300.

• Step 1: (change in cost / change in qty) (300 /50) = 6 is variable cost • Step 2 : fixed cost : 1300 – (200*6) = 100 • Step 3: total cost: 1900.

The product of two two-digit numbers is 2160 and their HCF is 12, find the numbers? • Step 1: undertake factorisation of 2160 • Step 2: find the numbers by multiplying un-common factors with the HCF = 5 is uncommon factor = 12*5 = 60 , so the other facor is 36. • Ans: 60 and 36

A merchant has 100 kg. of sugar, part of which he sells at 7% profit and rest at 17% profit, he gains 10% on the whole, how much did he sell at 17% Options: 35 Kg, 45 Kg., 30 Kg, 40 Kg.

• The answer is 30 Kg

What is Log 9 27 – log 27 9 = ? • 5/6 ans.

A is twice as fast as B, B is thrice as fast as C, if C takes 42 minutes, how much time will be taken by A in the same distance?

• 7 minutes.

Walking at 5/6th speed, I was late by 10 minutes, what is my usual time? • Step 1: there is invese relation between speed and time, so make an equation: • 6/5 time – usual time = 10 minutes • 6/5x –x = 10, so x = 50, ans.

Thanks • Afterschoool conducts three year integrated PGPSE (after class 12) and 18 month PGPSE (Post Graduate Programme in Social Entrepreneurship). It is free for all. It also conducts workshops on social entrepreneurship in schools and colleges all over India – start social entrepreneurship club in your institution today with the help from afterschoool and help us in developing society.

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