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TN 8th Tamil இயல் 2 - ஈடில்லா இயற்கை - இயற்கையை போற்றுவோம் Important Questions And Answers Study Material - QB365 Set A
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TN 8th Tamil இயல் 2-ஈடில்லா இயற்கை - திருக்குறள் Important Questions And Answers Study Material - QB365 Set A
Published on: 30/10/2019
Term 2 Life Mathematics
Download Tamil Nadu 8th Standard Maths question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.
Questions + Answers key
Take MCQ Maths Test1.
The bacteria in a culture grows by 5% in the first hour, decreases by 8% in the second hour and again increases by 10% in the third hour. Find the count of the bacteria at the end of 3 hours, if its initial count was 10000.
2.
The value of a motor cycle 2 years ago was Rs.70000. It depreciates at the rate of 4% p.a. Find its present value.
3.
If the population in a town has increased from 20000 to 25000 in a year, fi nd the percentage increase in population.
4.
When a number is decreased by 25% it becomes 120. Find the number.
5.
If x % of 600 is 450 then, find the value of x.
6.
A number when decreased by 20% gives 80. Find the number.
7.
If the difference between 75% of a number and 60% of the same number is 82.5, then find 20% of that number.
8.
What is 25% of 30%of 400?
9.
A bank pays Rs. 240 as interest for 2 years for a sum of Rs. 3000 deposited as savings. Find the rate of interest given by the bank.
10.
48 is 32% of what number?.
11.
Ranjith bought a washing machine for Rs. 16150 and paid Rs. 1350 for its transportation. Then, he sold it for Rs. 19250. Find his gain or loss percentage.
12.
If the selling price of a LED TV is equal to \(\frac{5}{4}\) of its cost price, then find the gain / profit percentage.
13.
The sum which amounts to Rs.2662 at 10% p.a in 3 years compounded yearly is_______.
Rs.2000
Rs.1800
Rs.1500
Rs.2500
14.
The number of conversion periods, if the interest on a principal is compounded every two months is___________.
2
4
6
12
15.
The single discount % which is equivalent to two successive discount of 20% and 25% is
40%
45%
5%
22.5%
16.
By selling a flower pot for Rs. 528, a woman gains 20%. At what price should she sell it to gain 25%?
Rs. 500
Rs. 550
Rs. 553
Rs. 573
17.
A fruit vendor sells fruits for Rs. 200 gaining Rs. 40. His gain percentage is
20%
22%
25%
16\(\frac { 2 }{ 3 } \)%
1.
Bacteria at the end of 3 hours
a = p\(\left( 1+\frac { a }{ 100 } \right) \left( 1-\frac { b }{ 100 } \right) \left( 1+\frac { c }{ 100 } \right) \)('-' because ‘decrease’)
= 10000\(\left( 1+\frac { 5 }{ 100 } \right) \left( 1-\frac { 8 }{ 100 } \right) \left( 1+\frac { 10 }{ 100 } \right) \)
= 10000 x \(\frac { 105 }{ 100 } \times \frac { 92 }{ 100 } \times \frac { 110 }{ 100 } \)
A = Rs.10626
2.
Depreciated value = P\({ \left( 1-\frac { r }{ 100 } \right) }^{ n }\)
= 70000\({ \left( 1-\frac { 4 }{ 100 } \right) }^{ 2 }\)
= 70000 x \(\frac { 96 }{ 100 } \times \frac { 96 }{ 100 } \)
= Rs.64512
3.
Increase in population = 25000 − 20000
= 5000
∴ Percentage increase in population =\(\frac { 5000 }{ 20000 } \)x 100
= 25%
4.
Let the number be x.
x-\(\frac { 25 }{ 100 } x\) = 120
\(\frac { 100x-25x }{ 100 } \) = 120
\(\frac { 75x }{ 100 } \) = 120
x = \(\frac { 120\times 100 }{ 75 } \)
x = 160
5.
x% of 600 = 450
\(\frac { x }{ 100 } \)× 600 = 450
\(x=\frac { 450 }{ 6 } \)
x = 75
6.
Let the number be x.
Given: x - 2 % of x = 80
\( x-\frac{20}{100} \times x=80 \)
\(x\left(1-\frac{20}{100}\right) =80 \)
\(x\left(\frac{80}{100}\right) =80 \)
\(\therefore x =\frac{80 \times 100}{80}\)
x = 100
The required number is 100.
7.
Let the numberbe x.
Given 75% of x - 60% of x = 82.5
\(
\frac{75}{100} x-\frac{60}{100} x =82.5
\)
\(\frac{x}{100}(75-60) =82.5
\)
\(\frac{x \times 15}{100} =82.5
\)
\(\therefore x=\frac{82.5 \times 100}{15}\)
x = 550
The required number is 550
\(20 \% \text { of } 550=\frac{20}{100} \times 550\)
= 110
8.
25% of 30% of 400
\(=25 \% \text { of }\left(\frac{30}{100} \times 400\right)\)
= 25% of 120
\(=\frac{25}{100} \times 120=30\)
25% of 30% of 400 = 30
9.
\(\frac{Pnr}{100}\)
\(240 = \frac{3000\times2 \times r}{100}\\ = \frac{240}{60}\)
R = 4%
10.
Let the number be x.
\( \frac{32}{100} \times x =48 \)
\(x =\frac{48 \times 100}{32}=150\)
The number is 150
11.
Total C.P of the washing machine
= C.P + Overhead Expenses
= 16150 + 1350 = Rs. 17500
S.P = Rs. 19250
Therefore, we find S.P > C.P.
Gain % = \(\left( \frac { Gain }{ C.P } \times 100 \right) %\)% = \(\left( \frac { 19250-17500 }{ 17500 } \times 100 \right) %\)
=\(\frac { 1750 }{ 17500 } \times 100\) = 10%
12.
Let the C.P of the LED TV be rs x.
∴ S.P = \(\frac { 5 }{ 4 } \)x
Profit = S.P – C.P = \(\frac { 5 }{ 4 } \)x - x = \(\frac { x }{ 4 } \)
∴Profit % =\(\left( \frac { Profit }{ C.P } \times 100 \right) %\)
=\(\left( \frac { { x }/{ 4 } }{ x } \times 100 \right) %\)
=\(\left( \frac { 1 }{ 4 } \times 100 \right) %\) = 25%
13.
(a)
Rs.2000
14.
(c)
6
15.
(a)
40%
16.
(b)
Rs. 550
17.
(c)
25%
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Tamilnadu Stateboard 8th Standard Subjects
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