Mathematics
How many two digit numbers are divisible by 3?
AP
2 Likes
Answer
Two digit numbers divisible by 3 are,
12, 15, 18, ………, 99.
The above sequence is an A.P. with d = 3.
Let 99 be nth term.
∴ an = 99
⇒ 12 + 3(n - 1) = 99
⇒ 12 + 3n - 3 = 99
⇒ 3n + 9 = 99
⇒ 3n = 90
⇒ n = 30.
Hence, 30 two digit numbers are divisible by 3.
Answered By
1 Like
Related Questions
Refer the given sequence 23, , 20, ….
(a) Find the general term of the given sequence.
(b) Which term is the last positive term in the sequence.
Case study:
Cable cars, at hill stations, are major tourist attractions. On a hill station, the length of a cable car ride from the base to the topmost point on the hill is 5000 m. Poles are installed at equal intervals on the way to provide support to the cable on which the car moves.The distance of the first pole from the base point is 200 m and subsequent poles are installed at equal intervals of 150 m. Further, the distance of the last pole from the top is 300 m.
Based on above information, answer the following questions using Arithmetic Progression:
(i) Find the distance of the 10th pole from the base.
(ii) Find the distance between the 15th pole and 25th pole.
(iii) Find the time taken by the cable car to reach the 15th pole from the top if it is moving at a speed of 5 m/s and coming from the top.
Case study:
A school auditorium is to be constructed to accommodate at least 1500 people. The chairs are to be placed in a concentric circular arrangement in such a way that each succeeding circular row has 10 seats more than the previous one.(i) If the first circular row has 30 seats, how many seats will the 10th row have?
(ii) For 1500 seats in the auditorium, how many circular rows need to be there?
(iii) If there were 17 rows in the auditorium, how many seats will there be in the middle row?
Case study:
The figure shows a big triangle in which multiple other triangles can be seen. Observe the pattern of dark shaded and light unshaded triangles starting with one triangle in row 1, three triangles in row 2, five triangles in row 3 and so on.
Based on the above information, answer the following questions:
(i) How many triangles will be there in the 15th row?
(ii) In which row will the number of triangles be 47?
(iii) The number of dark shaded triangles in each row are in A.P. Find the total number of dark shaded triangles in the first 15 rows.