The simple interest ($@ 6\%$per annum) received on a principal of $₹X$ was $₹482.40$, when invested for $3$ years in scheme A. If scheme B offered compound interest at $10\%$ per annum, what is the interest received by investing $₹X-680$ for $2$ years in scheme B?

A rectangular garden of length $12 m$ is surrounded by a $2 m$ wide path. If the area of the garden is $84 m^2$ and the cost of gravelling is $₹8$ per $m^2$, then what is the total cost of gravelling the path?

Train A, travelling at $\mathrm{S} \mathrm{m}/\mathrm{s}$, can cross a platform double its length in $21$ seconds. The same train, travelling at $\mathrm{S}+5 \mathrm{m}/\mathrm{s}$, can cross the same platform in $18$ seconds. What is the value of $\mathrm{S}$?

Read the sentence to find out whether there is any grammatical or idiomatic error in it. The error, if any, will be in one part of the sentence. The number of that part is the answer. If there is 'No error', the answer is (5). (Ignore errors of punctuation, if any.)

(1) Harsh Vardhan said he was looking forward /(2) to serve his roots, as he had spend /(3) the first 15 years of his life /(4) in the streets of old Delhi. (5) No error