Nth Term of HP

Q.

If $a,b,c,d$ are in HP, then $ab+bc+cd$ is equal to

1. $3ad$

2. $(a+b)(c+d)$

3. $3ac$

4. none of these

Q.

The 4 term of a H.P is $\frac{3}{5}$ and 8th term is $\frac{1}{3}$, then its 6th term is

1. 

2. 

3. 

4. 

Q.

If ${}^{n}P_r=30240$ and ${}^{n}C_r=252$, then the ordered pair $\left(n,r\right)$ is equal to?

1. $\left(12,6\right)$

2. $\left(10,5\right)$

3. $\left(9,4\right)$

4. $\left(16,7\right)$

Q.

The first term of a H P whose second term is $\frac{5}{2}$ and third term is $\frac{10}{3}$, is___

Q.

The fifth of the H.P. 2, $\frac{5}{2}$, $\frac{10}{3}$, ................. will be

1. 

2. 

3. 10

4. 

Q.

If sixth term of a H.P. is $\frac{1}{61}$ and its tenth term is $\frac{1}{105}$, then first term of that H.P. is

1. 

2. 

3. 

4. 

Q.

If the $7^{th}$ term of a harmonic progression is 8 and the $8^{th}$ term is 7, then its ${15}^{th}$ term is

1. 

2. 16

3. 14

4. 

Q.

If the 7th term of a H.P is $\frac{1}{10}$ and the 12th term is $\frac{1}{25}$, then the 20th term is

1. 

2. 

3. 

4. 

Q.

If the $m^{th}$ term of a H.P. be n and $n^{th}$ be m, then the $r^{th}$ term will be

1. 

2. 

3. 

4. 

Q.

The first term of a harmonic is $\frac{1}{7}$ and the second term is $\frac{1}{9}$. The ${12}^{th}$ term is

1. 1/19

2. 1/29

3. 1/17

4. 1/27