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Insert 5 geometric means between (1)/(3)...

Insert 5 geometric means between `(1)/(3)` and 243.

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To insert 5 geometric means between \( \frac{1}{3} \) and 243, we will follow these steps: ### Step 1: Identify the first and last terms The first term \( a \) is \( \frac{1}{3} \) and the last term (7th term) \( a_7 \) is 243. ### Step 2: Use the formula for the nth term of a geometric progression The nth term of a geometric progression is given by: \[ a_n = a \cdot r^{n-1} \] Here, \( a_7 = a \cdot r^{6} \) (since we have 5 terms in between, making it the 7th term). ### Step 3: Set up the equation Substituting the known values into the equation: \[ 243 = \frac{1}{3} \cdot r^{6} \] ### Step 4: Solve for \( r^6 \) To eliminate \( \frac{1}{3} \), multiply both sides by 3: \[ 3 \cdot 243 = r^{6} \] \[ 729 = r^{6} \] ### Step 5: Find \( r \) Now, take the sixth root of both sides: \[ r = 729^{\frac{1}{6}} \] Since \( 729 = 3^6 \), we have: \[ r = 3 \] ### Step 6: Calculate the geometric means Now that we have \( r \), we can find the 5 geometric means: 1. First term: \( a = \frac{1}{3} \) 2. Second term: \( a \cdot r = \frac{1}{3} \cdot 3 = 1 \) 3. Third term: \( a \cdot r^2 = \frac{1}{3} \cdot 3^2 = \frac{1}{3} \cdot 9 = 3 \) 4. Fourth term: \( a \cdot r^3 = \frac{1}{3} \cdot 3^3 = \frac{1}{3} \cdot 27 = 9 \) 5. Fifth term: \( a \cdot r^4 = \frac{1}{3} \cdot 3^4 = \frac{1}{3} \cdot 81 = 27 \) 6. Sixth term: \( a \cdot r^5 = \frac{1}{3} \cdot 3^5 = \frac{1}{3} \cdot 243 = 81 \) ### Step 7: List the geometric means The 5 geometric means between \( \frac{1}{3} \) and 243 are: 1. \( 1 \) 2. \( 3 \) 3. \( 9 \) 4. \( 27 \) 5. \( 81 \) ### Final Answer The 5 geometric means between \( \frac{1}{3} \) and 243 are \( 1, 3, 9, 27, \) and \( 81 \). ---
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ICSE-SEQUENCE AND SERIES -EXERCISE 14 (e)
  1. Find: (i) the 7th term of 2,4,8,... (ii) the 9th term of 1,(1)/(2),(1)...

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  2. The second term of a G.P. is 18 and the fifth term is 486. Find: (i)...

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  3. Find the value of x for which x +9,x-6, 4 are the first three terms of...

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  4. If 5, x, y, z, 405 are the first five terms of a geometric progression...

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  5. Insert 3 geometric means between 16 and 256.

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  6. Insert 5 geometric means between (1)/(3) and 243.

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  7. If the A.M. and G.M. between two numbers are respectively 17 and 8, fi...

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  8. The second, third and sixth terms of an A.P. are consecutive terms of ...

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  9. The 5th, 8th and 11th terms of a G.P. are P, Q and S respectively. Sho...

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  10. The (p+q)th term and (p-q)th terms of a G.P. are a and b respectively....

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  11. If the pth, th, rth terms of a G.P. are x, y, z respectively, prove th...

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  12. In a set of four numbers, the first three are in G.P. and the last thr...

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  13. If a^((1)/(x))= b^((1)/(y))= c^((1)/(z)) and a,b,c are in G.P., prove ...

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  14. If one G.M., G and two A.M's p and q be inserted between two given num...

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  15. Construct a quadratic equation in x such that the A.M. of its roots is...

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  16. The fourth term of a G.P. is greater than the first term, which is pos...

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  17. The first, eighth and twenty-second terms of an A.P. are three consecu...

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