Question

In a rangoli design of thirteen rows, every
row increases its previous row by two dots
and first row contains 5 dots, then how many
total dots are in the design?​

Answer 1

Answer:

89 dots are there in the design

Answer 2

The total number of dots are 221.

Step-by-step explanation:

Consider the provided information.

It is given that the total number of rows are 13. Each row is increased by 2  dots and first row has 5 dots.

We need to find the total number of dots.

Therefore, n=13, d=2, a=5, Sn=?

Use the formula: $S_n=\frac{n}{2}[2a+(n-1)d]$

Substitute the respective values in the above formula.

$S_n=\frac{13}{2}[2(5)+(13-1)2]$

$S_n=\frac{13}{2}[10+24]$

$S_n=\frac{13}{2}[34]$

$S_n=13\times17$

$S_n=221$

Hence, the total number of dots are 221.

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