SSC CPO Tier 1 Exam 04 Oct 2023 Shift 1

Anandi bought a smart watch from an electronic store for Rs.4,400. Since she had less money, she paid Rs.2,000 for down payment and the shopkeeper offered her an alternative to pay Rs.2,440 after 1 month. Find the rate of interest being charged at simple interest by the shopkeeper in this instalment option?