FTSE 100 slips as earnings disappoint

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* FTSE 100 down 0.1%, FTSE 250 up 0.1%

* U.S.-China trade deal signed but doubts linger

* Pearson, Whitbread drag blue-chips lower

* ABF outshines main index

* Wood Group surges on midcaps

Jan 16 (Reuters) - London’s main index inched lower on Thursday as companies, including Pearson and Whitbread, gave dismal trading updates, while sentiment was subdued as some key elements of the U.S.-China trade deal were not clear.

China will boost purchases of U.S. goods and services by $200 billion over two years in exchange for the rolling back of some tariffs under the deal.

The Phase 1 deal, however, does not fully eliminate the tariffs, while the purchase targets, which include energy, farm and manufacturing products, look daunting to achieve.

The FTSE 100 gave up 0.1%, with education company Pearson sinking 12% to its lowest level since October 2008 and Premier Inn-owner Whitbread slipping 6%, as the corporate earnings season kicked into high gear.

Associated British Foods outperformed the blue-chip bourse, as it rose 3% after it posted solid revenue growth at its Primark fashion chain and stood by its annual earnings forecast.

The midcap FTSE 250 gained 0.1%, helped by a 9% surge in Wood Group after the oilfield services provider forecast higher 2019 core earnings. (Reporting by Shashwat Awasthi in Bengaluru; Editing by Anil D’Silva)