Price Index

Dear Mr Moffat I came across to below question for which I don't understand and agree with the answer provided in the book Could you kindly revise my working and point out the mistake if there is any? Product M uses four different type of materials. The materials used and their prices in 2006 and 2007 are as follows: 2006 Material A kg 200 $0.98 Material B Kg 500 $ 0.95 Material C Kg 300 $1.20 Material D Kg 400 $1.10 2007 Material A kg 300 $1.40 Material B Kg 400 $1.10 Material C Kg 500 $0.92 Material D Kg 100 $1.14 Calculate the Laspeyre quantity index for 2007 (with 2006 as the base year) to two decimal places. My working As Laspeyre takes the base qty , where Paasque current qty. 2006 Material A kg 200 $0.98 Material B Kg 500 $ 0.95 Material C Kg 300 $1.20 Material D Kg 400 $1.10 Total 1471 2007 Material A kg 200 $1.40 Material B Kg 500 $1.10 Material C Kg 300 $0.92 Material D Kg 400 $1.14 Total 1562 1562/1471*100 106.19 Book answer 2006 Material A kg 200 $0.98 Material B Kg 500 $ 0.95 Material C Kg 300 $1.20 Material D Kg 400 $1.10 2007 Material A kg 300 $0.98 Material B Kg 400 $0.95 Material C Kg 500 $1.20 Material D Kg 100 $1.10 1384/1471*100 94.09 Since when do we need to use the price for the base year and not base qty to calculate the price index. I think this is a mistake. Please correct me if I am wrong. Thanks a lot for your help Gabbi