A hall has 35 rows. Each successive row contains two additional seat. If the first row has 20 seats, how many seats are in the hall?

There are 1,890 seats in the hall

Step-by-step explanation:

The number of seats in the first row = 20 seats

The number of rows in the hall = 35 rows

The number of additional seat per row = 2 Seat

Therefore, the sequence of seats in the hall is an arithmetic sequence with the first term, a = 25, the common difference, d = 2, and the number of terms, n = 35

The formula for finding the sum of n-terms of an arithmetic progression, Sₙ is given as follows;

Sₙ = n/2 × [2·a + (n  - 1)·d]

Plugging in the values, we get;

Sₙ = 35/2 × [2 × 25 + (35  - 1)×2] = 1890 seats

Therefore, there are 1,890 seats in the hall.

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step-by-step explanation: