1. © mathsheuristics  The average height of a group of children was 139.4 cm. The height of one of the child was recorded wrongly as 129 cm. His correct height was 192 cm. The correct average height of the children became 142.4 cm. How many children were there in the group? No of children  1u Ave height  139.4 Total height  139.4 x 1u = 139.4u 1

2. © mathsheuristics  The average height of a group of children was 139.4 cm. The height of one of the child was recorded wrongly as 129 cm. His correct height was 192 cm. The correct average height of the children became 142.4 cm. How many children were there in the group? No of children  1u Ave height  139.4 Total height  139.4 x 1u = 139.4u 139.4u 1

3. © mathsheuristics  The average height of a group of children was 139.4 cm. The height of one of the child was recorded wrongly as 129 cm. His correct height was 192 cm. The correct average height of the children became 142.4 cm. How many children were there in the group? No of children  1u Ave height  139.4 Total height  139.4 x 1u = 139.4u 139.4u 129 cm 1 2

4. © mathsheuristics  The average height of a group of children was 139.4 cm. The height of one of the child was recorded wrongly as 129 cm. His correct height was 192 cm. The correct average height of the children became 142.4 cm. How many children were there in the group? No of children  1u Ave height  139.4 Total height  139.4 x 1u = 139.4u 139.4u 129 cm 192 cm 63 cm 1 2

5. © mathsheuristics  The average height of a group of children was 139.4 cm. The height of one of the child was recorded wrongly as 129 cm. His correct height was 192 cm. The correct average height of the children became 142.4 cm. How many children were there in the group? No of children  1u Ave height  139.4 Total height  139.4 x 1u = 139.4u 139.4u 129 cm 192 cm 63 cm Ave height  142.4 Total height  142.4 x 1u = 142.4u 1 2 3

6. © mathsheuristics  The average height of a group of children was 139.4 cm. The height of one of the child was recorded wrongly as 129 cm. His correct height was 192 cm. The correct average height of the children became 142.4 cm. How many children were there in the group? No of children  1u Ave height  139.4 Total height  139.4 x 1u = 139.4u 139.4u 129 cm 192 cm 63 cm Ave height  142.4 Total height  142.4 x 1u = 142.4u 142.4u 1 2 3

7. © mathsheuristics  The average height of a group of children was 139.4 cm. The height of one of the child was recorded wrongly as 129 cm. His correct height was 192 cm. The correct average height of the children became 142.4 cm. How many children were there in the group? No of children  1u Ave height  139.4 Total height  139.4 x 1u = 139.4u 139.4u 129 cm 192 cm 63 cm Ave height  142.4 Total height  142.4 x 1u = 142.4u 142.4u 1 2 3 4 142.4u –139.4u  63

8. © mathsheuristics  The average height of a group of children was 139.4 cm. The height of one of the child was recorded wrongly as 129 cm. His correct height was 192 cm. The correct average height of the children became 142.4 cm. How many children were there in the group? No of children  1u Ave height  139.4 Total height  139.4 x 1u = 139.4u 139.4u 129 cm 192 cm 63 cm Ave height  142.4 Total height  142.4 x 1u = 142.4u 142.4u 3u  63 1u  63 ÷ 3 =21 Ans: 21 children 1 2 3 4 142.4u –139.4u  63