CKMMWX    CKMMWX    CKMMWX    CKMMWX    CKMMWX    CKMMWX    CKMMWX    
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                              ******

SUBROUTINE CKMMWX (X, ICKWRK, RCKWRK, WTM)
Returns the mean molecular weight of the gas mixture given mole
fractions.

INPUT
X(*)      - Real array, mole fractions of the mixture;
            dimension at least KK, the total species count.
ICKWRK(*) - Integer workspace array; dimension at least LENICK.
RCKWRK(*) - Real    workspace array; dimension at least LENRCK.

OUTPUT
WTM       - Real scalar, mean molecular weight of the mixture.
               cgs units, gm/mole