Word problems with extra or missing information

Key Notes :

1. Understanding Word Problems

  • Word problems involve translating a real-world situation into a mathematical equation or operation.
  • The key to solving these problems is identifying the relevant information and disregarding irrelevant details.

2. Extra Information

  • Sometimes, word problems include information that is not needed to solve the problem. This extra information may be meant to confuse or mislead.
  • How to handle extra information: Identify the core information you need for the solution, and ignore the extra details.
  • Example:
    • Problem: Sarah has 5 apples. She buys 3 more apples and gives 2 apples to her friend. How many apples does she have now?
    • Extra information: “She gives 2 apples to her friend.”
    • Correct approach: Focus only on the apples she had initially and bought (5 + 3 = 8 apples), and subtract the ones she gave away (8 – 2 = 6 apples).

3. Missing Information

  • Word problems sometimes provide incomplete data, and the solution requires you to find the missing information.
  • How to handle missing information: Set up a variable or equation to represent the missing information, then solve for it.
  • Example:
    • Problem: John has some candies. He buys 4 more candies and now has 10 candies. How many candies did he start with?
    • Missing information: The number of candies John started with.
    • Solution: Let the number of candies John started with be represented by “x”. The equation is:
      x+4=10 Solving for x:
      x=10−4=6
    • John started with 6 candies.

Learn with an example

1) Oliver took a train from Chesterton to Riverside by way of Watertown and Salem. The train went 10 kilometers from Chesterton to Watertown. 7 passengers got on at Watertown. It was 5 kilometers from Salem to Riverside.

How many kilometres was Oliver’s train ride?

  • 28
  • 27
  • 17
  • There is not enough information to solve this problem.

There is not enough information to solve this problem. You need to know how far it was from Watertown to Salem.

2) Tessa took the train from Walnut City to Almondburg by way of Peanut Village and Pecan Harbour. The train went 20 kilometres from Walnut City to Peanut Village. It was 5 kilometres from Pecan Harbour to Almondburg.

How many kilometres was Tessa’s train ride?

  • 22
  • 21
  • 32
  • There is not enough information to solve this problem

There is not enough information to solve this problem. You need to know how far it was from Peanut Village to Pecan Harbour.

3) Roger bought 8 large marbles and 13 bags of small marbles.

How many marbles did Roger buy in all?

  • 96
  • 86
  • 87
  • There is not enough information to solve this problem

There is not enough information to solve this problem. You need to know how many marbles were in each bag.

Let’s practice!🖊️