These must be books for young children
5 * 1.8 = 9
1.4 + 1.9 + 2.1 * 2.4 + x = 9
Solve for x.
The librarian was checking the thicknesses of several books and found that the average thickness of a book was 1.8 centimeters. She found this by averaging the thickness of five different books. Four of the thicknesses were 1.4cm, 1.9 cm, 2.1 cm, and 2.4 cm. What was the thickness of the fifth book that she measured?
2 answers
The librarian measured the thickness of the textbooks in the school library. Among a selection of 7 books, he recorded the following thicknesses: