Question
Question: 10 equi spaced horizontal lines are intersected by 12 equi spaced vertical lines. If the distance be...
10 equi spaced horizontal lines are intersected by 12 equi spaced vertical lines. If the distance between two successive horizontal lines is same as that between two successive vertical lines the number of squares formed by the lines is –
A
365
B
385
C
375
D
395
Answer
375
Explanation
Solution
Total number of ways = ∑r=1m−1(m−r)(n−r)
m = 10, n = 12
= 9.11 + 8.10 + 7.9 + 6.8 + 5.7 + 4.6 + 3.5 + 2.4 + 1.3
= 99 + 80 + 63 + 48 +35 + 24 + 15 + 8 + 3
= 375.