Question

4.2 Fig. 13 shows a train where the train coaches are of
equal sizes and are at an equal distance from one another. The lengths of the engine and the coach are 15 m and 20 m, respectively. The distance between two adjacent coaches is 3 m. Write down an expression to
show the length of the train if there are n coaches in the
train​

Answer 1

Answer:

The length of the train will be (23n+12) m.

Explanation:

Given: Length of engine = 15 m , length of a coach = 20 m , distance between two adjacent coaches = 3 m and number of coaches = n

Let the total length of the train be y.

If there are 2 coaches, then distance between them will be counted once only.

If there are 3 coaches, then distance between them will be counted twice.

Similarly, if there are n coaches, then distance between them will be counted (n-1) times.

So, the total length of the train = (length of engine) + (number of coaches)×(length of each coach) + (distance between two adjacent coaches)×(number of times they are counted)

⇒ y = 15 + 20n + 3(n-1)

⇒ y = 15 + 20n + 3n - 3

⇒ y = 23n + 12

So, the length of the train will be (23n+12) m.

Answer 2

length of engine=15m

length of coach =20m

distance between two adjacent coach =3m

number of coach=n

let length of train be =x

x=15+20n X n+4(n_1)

x=15+20n+3n_3

x=23n+12

Explanation:

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