Advertisements
Advertisements
Question
Ramkali saved Rs 5 in the first week of a year and then increased her weekly saving by Rs 1.75. If in the nth week, her week, her weekly savings become Rs 20.75, find n.
Advertisements
Solution
Given that,
a = 5
d = 1.75
an = 20.75
n = ?
an = a + (n − 1) d
⇒ 207.50 = 50 + (n - 1) (17.5)
⇒ 207.50 = 50 + 17.5n - 17.5
⇒ 17.5n = 207.50 + 17.5 - 50
⇒ 17.5n = 225 - 50
⇒ 17.5n = 175
⇒ n = `175/17.5`
⇒ n = 10
Hence, n is 10.
RELATED QUESTIONS
Find the sum of first 30 terms of an A.P. whose second term is 2 and seventh term is 22
A small terrace at a football field comprises 15 steps, each of which is 50 m long and built of solid concrete. Each step has a rise of `1/4` m and a tread of `1/2` m (See figure). Calculate the total volume of concrete required to build the terrace.
[Hint: Volume of concrete required to build the first step = `1/4 xx 1/2 xx 50 m^3`]
If the sum of first m terms of an A.P. is the same as the sum of its first n terms, show that the sum of its first (m + n) terms is zero
Find the sum of all natural numbers between 200 and 400 which are divisible by 7.
In a school, students decided to plant trees in and around the school to reduce air pollution. It was decided that the number of trees, that each section of each class will plant, will be double of the class in which they are studying. If there are 1 to 12 classes in the school and each class has two sections, find how many trees were planted by the students.
If the sum of P terms of an A.P. is q and the sum of q terms is p, then the sum of p + q terms will be
A sum of Rs. 700 is to be paid to give seven cash prizes to the students of a school for their overall academic performance. If the cost of each prize is Rs. 20 less than its preceding prize; find the value of each of the prizes.
Find the sum of three-digit natural numbers, which are divisible by 4.
In an AP, if Sn = n(4n + 1), find the AP.
If the first term of an A.P. is p, second term is q and last term is r, then show that sum of all terms is `(q + r - 2p) xx ((p + r))/(2(q - p))`.
