A family in Singapore part 47 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings about Solving Singapore Primary School Mathematics. The blog presenting the Math Concept, the Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids will able to acquire knowledge of dealing with the Math Modeling, the Math Problem Solving and the Problem Sum from Lower Primary School to Upper Primary School level after reading the blog postings. This posting is an upper primary school math question on Algebra, Ratio and Problem Sum.

You can click here and read the posting  A family in Singapore about Sarin’s family.

Read the posting on Sarin learns concept of ratio in school to understand the concept of Ratio.

Read also the posting on Sarin learns Symbol, Algebra and Equation in school (Math Concept) to understand the concept of Algebra.

Challenge yourself with the question before look for the given solution‼!

Upper primary school mathematics question UPQ409

Fatimah’s father is 48 years old and Fatimah is 6 years old. In how many years’ time will Fatimah’s father be four times as old as Fatimah?

 Solution:

            Using Algebra Expression

            Whenever a year pass, both Fatimah and her father will be additional 1 year older

            After Some years (x),

            Fatimah will be (6 + x) years old

            Fatimah’s father will be (48 + x) years old

            Fatimah’s father is 4 times as old as Fatimah

            Fatimah’s age after x years will be = 4 (6 + x) = (24 + 4x)

            The model

UPQ409-1

            From the model

            3 units = 48 – 24 = 24

            1 unit = x = 8 years

            In 8 years times, Fatimah’s father will be 4 times as old as Fatimah

Alternative Solution(1):

                        After some years

UPQ409-2

                        Father’s age is 4 times of Fatimah’s age

                        Rearrange the model with the above information

UPQ409-3

                        From the above model

                        3 units = 48 – 6 = 42

                        1 unit = 14 years

                        The some years = 14 – 6 = 8 years

            In 8 years times, Fatimah’s father will be 4 times as old as Fatimah

Alternative Solution(2):

                        Sub-divide the some years more to 4 parts and redraw the model

 UPQ409-4

                        From the model

                        3 units = 12 – 6 = 6 years

                        1 unit = 2 years

                        The number of years = 2 × 4 = 8 years

            In 8 years times, Fatimah’s father will be 4 times as old as Fatimah

Alternative Solution(3):

            Express using ratio

            Present age ratio

            The ratio of Father’s age to Fatimah’s age = 48 : 6

            Age ratio after some years (x)

            The ratio of Father’s age to Fatimah’s age = 4 : 1 =  (48 + x) : (6 + x)

            48 + x = 4 × (6 + x)

            48 + x = 24 + 4x

            3x = 48 – 24 = 24

            x = 8 years

            In 8 years times, Fatimah’s father will be 4 times as old as Fatimah

More Questions on Ratio and Fraction. Click here….

More Questions on Algebra. Click here….

More Questions on Problem Sum. Click here….

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