The table below gives the atomic mass and relative abundance values for the three isotopes of element M. Relative abundance (%) Atomic mass (amu) 78.99 23.9850 10.00 24.9858 11.01 25.9826 What is the average atomic mass (in amu) of element M? 2.86 5.36 24.30 24.98

To calculate the average atomic weight, each exact atomic weight is multiplied by its percent abundance, then add the results together and round off to an appropriate number of significant figures. So according to what's given, the average atomic mass of element M should be (23.9850*0.7899) + (24.9858*0.1000) + (25.9826*0.1101) = 24.30