Gce Model Questions Vol1 2020 Commerce Question 14

A consumer can choose between two mobile‑data plans for the next 12 months.\ \nPlan X: fixed monthly fee \(\text{₦}5{,}000\), data at \(\text{₦}800\) per GB, and a one‑time activation fee \(\text{₦}2{,}000\) that is waived if a 12‑month contract is signed.\ \nPlan Y: no fixed monthly fee, a subscription fee \(\text{₦}1{,}200\) per month, and tiered data charges - first 5 GB at \(\text{₦}1{,}000\) per GB, next 5 GB at \(\text{₦}700\) per GB, and any usage above 10 GB at \(\text{₦}500\) per GB. A one‑time device subsidy of \(\text{₦}3{,}000\) is given if a 24‑month contract is signed.\ \nAssuming the consumer will use exactly 12 GB each month for the next 12 months and will sign the contract that gives the lowest net cost, which plan is cheaper and by how much (to the nearest naira)?