Question

Ramkali saved Rs. 5 in the first week of a year and then increased her weekly savings by Rs 1.75. If in the \(n^{th}\) week, her weekly savings become Rs 20.75, find n.

Answer 1

Given that,
\(a = 5\), \(d = 1.75\) and \(a_n = 20.75\).
\(n = ?\)
\(a_n = a + (n − 1) d\)
\(20.75 = 5 + (n-1)1.75\)
\(15.75 = (n-1)1.75\)
\(n-1 = \frac {15.75}{1.75}\)

\(n-1 = \frac {1575}{175}\)

\(n-1 = \frac {63}{7}\)
\(n − 1 = 9\)
\(n = 10\)

Hence, n is 10.