Such a statement cannot be made as it would mean that the results were misinterpreted. The survey asked students if they studied in the week not if they studied in the weekend therefore simply inferring from those who said they studied during the week would be an error.
Some of the 60% who study in the week might also study during the weekend which would increase the 40% figure said to study in the weekend. Some of the students who said they don't study in the week might not study in the weekend either thereby reducing the 40% figure. For these two reasons and others, this statement cannot be made.
