6. (5 points) The average of numbers $a, b, c, d$ is 7.1, and $2.5 \times a=b-1.2=c+4.8=0.25 \times d$, then $a \times b \times c$ $\times d=$ $\qquad$
【Solution】Solution: Let $2.5 \times a=b-1.2=c+4.8=0.25 \times d=x$, then $a=0.4 x, b=x+1.2, c=x-4.8, d=4 x$,

Since $a+b+c+d=7.1 \times 4=28.4$,
Therefore $0.4 x+(x+1.2)+(x-4.8)+4 x=28.4$,
Solving for $x=5$,
Thus $a=2, b=6.2, c=0.2, d=20$,
Therefore $a \times b \times c \times d=2 \times 6.2 \times 0.2 \times 20=49.6$.
The answer is: 49.6.