When a central bank lowers its interest rate, borrowing becomes cheaper and saving becomes less rewarding, so spending and investment may rise. When it raises the rate, the opposite happens. The skill is to write this as a chain, step by step, with each link explained.
This lesson sits in public finance and economic instruments and uses the percentage skills from reading a fictional budget.
What is the chain?
Think of the effect as a series of linked steps:
- The central bank changes its interest rate.
- Commercial banks change the rates on loans and savings accounts.
- The cost of borrowing changes, so some firms and households borrow more or less.
- Spending on consumption and investment changes.
- Total demand changes, and with it output, jobs and possibly prices.
Each arrow is a place where you can write “because”. A weak answer lists the steps with no reasons. A strong answer says why each one follows.
How do you test one link with numbers?
Interest cost on a loan = amount borrowed × interest rate. Compare the cost before and after the change, then compare it with the extra income the loan is expected to bring.
Worked example
In the fictional economy of Marlow, the central bank cuts its rate and the main loan rate for firms falls from 6% to 4%.
Delta Bakery plans to borrow MD 200,000 for a new oven. It expects the oven to add MD 10,000 a year to profit before interest.
Step 1, cost at 6%: 200,000 × 6% = MD 12,000 a year.
Step 2, net gain at 6%: 10,000 − 12,000 = −MD 2,000. The oven loses money after interest, so Delta Bakery does not borrow.
Step 3, cost at 4%: 200,000 × 4% = MD 8,000 a year.
Step 4, net gain at 4%: 10,000 − 8,000 = +MD 2,000. The oven now pays for itself, so Delta Bakery borrows and invests.
Step 5, wider chain: the oven purchase is spending that becomes income for the oven maker, so total demand may rise. This holds if other firms react in the same way and if confidence stays steady.
The mistake to watch for
A common slip is to skip the middle of the chain.
Mistaken answer: The interest rate falls, so prices rise.
The student jumped from the first link to the last and gave no reason for the steps between.
The correction is to write at least three linked steps: lower rate, cheaper borrowing, more spending, higher demand, and then state any effect on prices as a possibility that depends on spare capacity.
Check yourself
Try these without a calculator, then open each answer.
1. A firm borrows MD 40,000. Find the yearly interest at 5% and at 3%, and the saving.
Show answer
At 5%: 40,000 × 5% = MD 2,000. At 3%: 40,000 × 3% = MD 1,200. Saving = 2,000 − 1,200 = MD 800 a year.
2. A saver has MD 10,000 in a deposit. Interest falls from 2% to 1%. How much less interest does the saver earn a year?
Show answer
At 2%: MD 200. At 1%: MD 100. The saver earns MD 100 less, so saving is less rewarding.
3. Give one reason why a rate cut might not raise spending.
Show answer
Households and firms may lack confidence and choose not to borrow, or banks may not pass the cut on to borrowers. Either reason breaks a link in the chain.
Where this leads next
The same chain method applies to tax and spending in explaining possible fiscal effects and assumptions. Try the public finance practice set when you are ready, and use the percentage-base explorer to check interest calculations.
If you find the chain easy to say but hard to write, a teacher in online one-to-one Economics tuition can read your answer and mark where each link needs a reason.