All sections

Ratio and Rate

Chapter 9 Study Notes · O-Level 4052

Start Practice
Section 7 of 8
Contents▾
9.1Why Ratio and Rate Matter9.2Ratios and Equivalent Ratios9.3Dividing a Quantity in a Given Ratio9.4Rates and Unit Rates9.5Speed, Distance and Time9.6Simple Interest9.7Financial ApplicationsChapter Summary

9.7Financial Applications

Hire purchase pays a deposit, then the same sum monthly, so the total is the deposit plus every instalment. Currency exchange multiplies by the rate.

  • Hire purchase costs more than the cash price, and the difference is the financing charge
  • GST (Goods and Services Tax) in Singapore is 9%, applied to the price before tax
  • Commission is a bank or money-changer fee for currency exchange, usually a percentage of the SGD amount

Hire purchase cost and extra charge

A television costs $1800\displaystyle \$1800 cash. On hire purchase it takes a 20%\displaystyle 20\% deposit and 24 instalments of $72\displaystyle \$72. Find the extra cost.

Show solution▾
Deposit\displaystyle \text{Deposit}
=20%×$1800\displaystyle = 20\% \times \$1800
=$360\displaystyle = \$360
Total instalments\displaystyle \text{Total instalments}
=24×$72\displaystyle = 24 \times \$72
=$1728\displaystyle = \$1728
Total hire purchase cost\displaystyle \text{Total hire purchase cost}
=$360+$1728\displaystyle = \$360 + \$1728
=$2088\displaystyle = \$2088
Cash price$1800Hire purchase$360$1728$2088extra $288the same television, two ways to pay
Extra cost\displaystyle \text{Extra cost}
=$2088−$1800\displaystyle = \$2088 - \$1800
=$288\displaystyle = \$288

Currency exchange with commission

Mei Ling changes S$2000 to yen at S$1 = ¥110, with 1.5% commission on the SGD. How many yen does she get?

Show solution▾
Commission\displaystyle \text{Commission}
=1.5%×$2000=$30\displaystyle = 1.5\% \times \$2000 = \$30
Net SGD after commission\displaystyle \text{Net SGD after commission}
=$2000−$30=$1970\displaystyle = \$2000 - \$30 = \$1970
Japanese yen received\displaystyle \text{Japanese yen received}
=1970×110\displaystyle = 1970 \times 110
=¥216 700\displaystyle = ¥216\,700

Now you try

Convert S$50\text{S}\$50 to USD if the exchange rate is S$1=US$ 0.75\text{S}\$1 = \text{US}\$\,0.75.

Show solution▾
S$50×0.75\text{S}\$50 \times 0.75
=US$ 37.5= \text{US}\$\,37.5

Want it marked, with hints, and a new question each time? Practise this →

Practise this

Questions on Ratio and Rate, marked as you go, with the working shown.

Practise Ratio and Rate

Copy a link to this chapter