Starter QuestionsStarter Questions

1. Calculate 8796 ÷ 100

2. What is 45 mins expressed as a fraction of an hour?

3. Calculate the area of a circle, with radius 4cm.

4. Finda) -6 – (-3) b) -8 ÷ 4

Learning IntentionLearning Intention

To show how to convert time from hours and minutes to decimals and back again

Hrs and Mins in Hrs and Mins in Decimal TimeDecimal Time

Converting Decimal Time to Hrs Mins

Hrs Mins to Decimal Hrs Mins to Decimal TimeTime

Converting Hrs Mins to Decimal Time

We already know :

1 hour =0.5 hours

21 hour =0.25 hour

43

hour =0.75 hour4

Example 1 :48 minutes to decimal is = 0.8 hr

Example 2 :2hr 15 minutes to decimal is = 2.25 hr

To change minutes to a decimal ‘divide by 60’

48 ÷ 60

2 + (15 ÷ 60)

Hrs Mins to Decimal Hrs Mins to Decimal TimeTime

To change minutes to a decimal time ‘divide by 60’

To convert back to hours and minutes we do the opposite :

To change decimal time to minutes ‘multiply by 60’

Converting Decimal Time to Hrs Mins

Hrs Mins to Decimal Hrs Mins to Decimal TimeTime

Example 1 : 0.7 hrs to minutes is = 42 mins

Example 2 :3.4 hrs to hours and minutes is

= 3 hrs 24 mins

Converting Decimal Time to Hrs Mins

To change decimal time to minutes ‘multiply by 60’

0.7 x 60

3 + (0.4 x 60)

Hrs Mins to Decimal Hrs Mins to Decimal TimeTime

Converting Decimal Time to Hrs Mins

Convert the following hrs and minutes into decimal time:

a) 24 minutes b) 40 minutes c) 2 hrs 36 minutes

Convert the following decimal time into hrs and minutes:

a) 0.35 hrs b) 3.2 hrs c) 0.85 hrs

d) 9 minutes e) 21 minutes f) 4 hrs 27 minutes

d) 6.9 hrs e) 0.8 hrs f) 1.65 hrs

Now try Ex 10.5Pg 99 Q1&2

Time Distance Time Distance SpeedSpeed

Converting Hrs Mins to Decimal Times