8th Standard Syllabus & Materials
8th Standard
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NEW8th Standard
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NEW8th Standard
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NEW8th Standard
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NEW8th Standard
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Published on: 02/11/2019
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 simple interest on a certain principal for 3 years at 10% p.a is Rs.300. Find the compound interest accrued in 3 years.
2.
Find the rate of compound interest at which a principal becomes 1.69 times itself in 2 years.
3.
A sum of money becomes Rs.18000 in 2 years and Rs.40500 in 4 years on compound interest. Find the sum.
4.
P’s income is 25% more than that of Q. By what percentage is Q’s income less than P’s?
5.
Find the rate of interest if the difference between C.I and S.I on Rs.8000 compounded annually for 2 years is Rs.20.
6.
Find the C.I on Rs.15000 for 3 years if the rates of interest are 15%, 20% and 25% for I, II and III years respectively.
7.
Find the compound interest for 2 \(\frac { 1 }{ 2 } \) years on Rs.4000 at 10% p.a if the interest is compounded yearly.
8.
A shopkeeper buys goods at \(\frac { 4 }{ 5 } \) of its marked price and sells them at \(\frac { 7 }{ 5 } \) of the marked price find his profit percentage.
9.
Some articles are bought at 2 for Rs.15 and sold at 3 for Rs. 25. Find the gain percentage
10.
If selling an article for Rs. 820 causes 10% loss on the selling price, find its cost price
11.
A number is increased by 25% and then decreased by 20%. Find the percentage change in that number.
12.
A number when decreased by 20% gives 80. Find the number.
13.
If the difference between 75% of a number and 60% of the same number is 82.5, then find 20% of that number.
14.
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.
15.
48 is 32% of what number?.
1.
331
2.
Let P be the principal.
By the given data, the principal becomes 1.69 times itself after 2 years.
\(
\mathrm{A} =P\left(1+\frac{r}{100}\right)^{2}
\)
\(1.69 \mathrm{P} =P\left(1+\frac{r}{100}\right)^{2}
\)
\(1.69 =\left(1+\frac{r}{100}\right)^{2}
\)
\(1+\frac{r}{100} =1.3
\)
\(\frac{r}{100} =1.3-1 \)
\(\frac{r}{100} =0.3
\)
r = 30%
The rate of interest = 30%
3.
Rs.8000
4.
P's income = 25%
The percen(age of Q's income less than P's
\(
=\left(\frac{100 x}{100+x}\right) \%=\left(\frac{100 \times 25}{100+25}\right) \%
\)
\(=\left(\frac{100 \times 25}{125}\right) \%=20 \%
\)
i.e., The perlentage of Q's income less than P's = 20%
5.
P = Rs. 8000,
i = 2 years, Difference amount = Rs. 20
Difference between C.I and S.I for 2 years
\( =P\left(\frac{r}{100}\right)^{2} \)
\(20 =8000\left(\frac{r}{100}\right)^{2} \)
\(20 =8000 \times \frac{r^{2}}{10000} \)
\(20=\frac{4 r^{2}}{5} \)
\(r^{2} =\frac{20 \times 5}{4} \)
\(r^{2} =\frac{100}{4}=25\)
r = 5
the rate of interest = 57%
6.
\(
A =P\left(1+\frac{a}{100}\right)\left(1+\frac{b}{100}\right)\left(1+\frac{c}{100}\right)
\)
\(=15000\left(1+\frac{15}{100}\right)\left(1+\frac{20}{100}\right)\left(1+\frac{25}{100}\right.\)
\(=15000 \times \frac{115}{100} \times \frac{120}{100} \times \frac{125}{100}
\)
\(=15000 \times \frac{23}{20} \times \frac{24}{20} \times \frac{5}{4}
\)
A = Rs. 25875
C.I = A -P = 25875 - 10000
C.I = Rs. 10875
7.
\(
\text { Amount } =P\left(1+\frac{r}{100}\right)^{a}\left(1+\frac{\frac{b}{c} \times r}{100}\right)
\)
\(=4000\left(1+\frac{10}{100}\right)^{2}\left(1+\frac{\frac{1}{2} \times 10}{100}\right)
\)
\(=4000\left(\frac{110}{100}\right)^{2}\left(1+\frac{5}{100}\right)
\)
\(=4000 \times \frac{11}{10} \times \frac{11}{10} \times \frac{21}{20}\)
= 2 x 11 x 11 x 2
A = Rs. 5082
C.I = A - P
= 5082 - 4000 = 1082
C.I = Rs. 1082
8.
60%
9.
Let x be the total number of articles
\(\therefore \ \text { C.P }=\frac{15}{2} \times x \text { and S.P }=\frac{25}{3} \times x\)
Gain = S.P-C.P
\(=\frac{25}{3} x-\frac{15}{2} x\)
\(=\frac{50 x-45 x}{6}=\frac{5 x}{6}\)
Gain percentage \( =\frac{6}{\frac{15 x}{2}} \times 100 \)
\(=\frac{5 x}{6} \times \frac{2}{15 x} \times 100=\frac{100}{9} \)
\(=11 \frac{1}{9} \% \)
10.
Let x be the cost price of the article.
x-10% of x = 820
\(x-\frac{10}{100} x=820\)
\( \frac{90 x}{100} =820 \)
\(\frac{9}{10} x =820 \)
\(x =\frac{8200}{9}=911.11\)
Rs.911.11
11.
Let x and y be the increased and decreased percentage
The change in that number \(=\left(x+y+\frac{x y}{100}\right) \%\)
\(
=\left(25+(-20)+\frac{25(-20)}{100}\right) \% \)
\(=\left(25-20-\frac{500}{100}\right) \)
\(=(25-20-5) \%
\)
= 0%
There is no percentage changes in that number.
12.
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.
13.
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
14.
\(\frac{Pnr}{100}\)
\(240 = \frac{3000\times2 \times r}{100}\\ = \frac{240}{60}\)
R = 4%
15.
Let the number be x.
\( \frac{32}{100} \times x =48 \)
\(x =\frac{48 \times 100}{32}=150\)
The number is 150
8th Standard Syllabus & Materials
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Tamilnadu Stateboard 8th Standard Subjects
Tamilnadu Stateboard Standards
