Advertisements
Advertisements
Question
There is an auditorium with 35 rows of seats. There are 20 seats in the first row, 22 seats in the second row, 24 seats in the third row and so on. Find the number of seats in the twenty-fifth row.
Solution
Number of seats in the first row = 20
a = 20
Increase in the number of seats in consecutive rows = 2
d = 2
To find the number of seats in the 25th row, find t25
tn = a + (n – 1)d ... (Formula)
∴ t25 = 20 + (25 – 1) x 2 ... (Substituting the values)
= 20 + (24 x 2)
= 20+48
∴ t25 = 68
Thus, the number of seats in the twenty-fifth row is 68.
APPEARS IN
RELATED QUESTIONS
If m times mth term of an A.P. is equal to n times its nth term, show that the (m + n) term of the A.P. is zero
In the following situation, involved make an arithmetic progression? and why?
The taxi fare after each km when the fare is ₹ 15 for the first km and ₹ 8 for each additional km.
Find n if the nth term of the following A.P. is 68
5, 8, 11, 14, ..........
For an A.P., find S7 if a = 5 and d = 4.
Write the sequence with nth term: an = 9 − 5n
Which of the following sequences are arithmetic progressions? For those which are arithmetic progressions, find out the common difference.
12, 2, −8, −18, ...
Find the nth term of the A.P. 13, 8, 3, −2, ...
If 10 times the 10th term of an A.P. is equal to 15 times the 15th term, show that 25th term of the A.P. is zero.
The 7th term of an A.P. is 32 and its 13th term is 62. Find the A.P.
Show that (a − b)2, (a2 + b2) and (a + b)2 are in A.P.
Find the common difference of the A.P. and write the next two terms \[0, \frac{1}{4}, \frac{1}{2}, \frac{3}{4}, . . . \]
If nine times ninth term is equal to the fifteen times fifteenth term, show that six times twenty fourth term is zero
The ratio of 6th and 8th term of an A.P. is 7:9. Find the ratio of 9th term to 13th term
In an A.P., a = 10 and d = −3 then find its first four terms
Find the first terms and common difference of an A.P. whose t8 = 3 and t12 = 52.
In an A.P. t10 = 57 and t15 = 87, then find t21
Write second and third term of an A.P. whose first term is 6 and common difference is – 3.
The next term of the A.P. : `sqrt(6), sqrt(24), sqrt(54)` is ______.
If –5, x, 3 are three consecutive terms of an A.P., then the value of x is ______.
Statement A (Assertion): `-5, (-5)/2, 0, 5/2`, .... is in Arithmetic Progression.
Statement R (Reason): The terms of an Arithmetic Progression cannot have both positive and negative rational numbers.
