About age, it is a common test in elementary school mathematics application problems. The following is a question and answer on the application for primary school age. Welcome to read!
meaning
This kind of question is named according to the content of the topic. Its main feature is that the age difference between them is unchanged, but the multiple relationship of their ages changes with age.
magnitude relation
The problem of age is often closely related to the problems of sum and difference, sum multiple and difference multiple, especially the solution of difference multiple. We should firmly grasp the characteristic of "the age difference remains unchanged".
Ideas and methods to solve problems
We can use the ideas and methods to solve the "time difference" problem.
Example 1 Dad is 35 years old and Liang Liang is 5 years old. How old is dad this year? What about next year?
Solution 35 ÷ 5 = 7 (degree) (35+ 1) ÷ (5+ 1) = 6 (degree)
A: This year, my father is seven times as old as Liang Liang, and next year, my father is six times as old as Liang Liang.
Mother is 37 years old and daughter is 7 years old. In a few years, my mother will be four times as old as my daughter.
solve
(1) How old is the mother than the daughter? 37-7 = 30 years old
(2) A few years later, the mother is four times as old as her daughter? 30(4- 1)-7 = 3 (year)
Column into a comprehensive formula (37-7) ÷ (4- 1)-7 = 3 (year).
A: After three years, the mother is four times as old as her daughter.
Three years ago, the age of father and son was 49. This year, the father is four times as old as his son. How old are father and son this year?
It is understood that the total age of father and son this year should be (3×2) years older than that of three years ago, and the total age of the two this year is 49+3× 2 = 55 (years old).
Taking the age of the son this year as 1 time, the sum of the ages of the father and son this year is equivalent to (4+ 1) times. Therefore, the age of my son this year is
55 \ u (4+1) =11(years old)
Father's age this year is 1 1× 4 = 44 (years old).
A: My father is 44 years old and my son is 1 1 year old.
Example 4 A said to B, "My age is your present age, and you are only 4 years old". B said to A, "When my age is your present age in the future, you will be 6 1 year old". What are the ages of Party A and Party B now?
solve
This involves three years: the past year, this year and the next year. List analysis:
Last year, this year, the next year.
One year old? △ years old? 6 1 year
B 4 years old? □ years old? △ years old
Two □ in the table represent the same number, and two △ represent the same number.
Because the age difference between two people is always equal: □-4 = △-□ = 6 1-△, that is, 4 □, △, 6 1 becomes arithmetic progression, so 6 1 should be three years older than 4, so the age difference between two people is (61.
A The age this year is △ = 6 1- 19 = 42 (years old).
B The age this year is □ = 42- 19 = 23 (years old).
A: A is 42 years old and B is 23 years old.
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