Harish started work at an annual salary of ₹5,00,000 and received an increment of ₹20,000 each year. After how many years did his income reach ₹7,00,000?
10 years
Explanation
The problem involves an Arithmetic Progression where the first term is ₹5,00,000 and the common difference is ₹20,000. Using the nth term formula, we find n=11, meaning the 11th year salary is ₹7,00,000. Since the starting year is the 1st year, it takes 10 years of increments to reach the 11th year.
Solution Steps
Step 1: Identify first term (a) = ₹5,00,000 and common difference (d) = ₹20,000.
Step 2: Use the nth term formula: a_n = a + (n - 1)d
Step 3: Substitute values: 7,00,000 = 5,00,000 + (n - 1) × 20,000
Step 4: Simplify: 2,00,000 = (n - 1) × 20,000, so n - 1 = 10, giving n = 11.
Step 5: Since n = 11 is the 11th year, the income reaches ₹7,00,000 after 10 years.