Relationship between Real Interest Rate and Employment The country of Kingsland is considering the introduction of a
  compulsory retirement saving scheme. Under this scheme all workers are
  required to save ten per cent of their annual wages and salaries until
  they retire. Use the supply and demand model (and a diagram) for
  saving and investment to explain the likely effects of this scheme on
  national saving, investment and the real interest rate in Kingsland.
  Explain the effects on employment of the saving scheme. (You can
  assume that Kingsland is a closed economy).


Since the level of national savings has increased, I understand how the savings curve shifts to the right and thus decreases the real interest rate and increases the levels of savings and investment in the economy. I am unable to understand how I can relate this back to the level of unemployment in the economy.
Recall that central banks use interest rate to control inflation by inducing spending or saving  with decrease or increase in interest rate.

Also,note the theory proposed by the short-run Phillips curve.



Though this graph has  some controversy in terms of its empirical soundness. It is the basis of how we tie interest rate to unemployment.

abstractly you can think of it as a "causal chain" being:
$$\text{interest rate}\rightarrow\text{savings rate}\rightarrow\text{spending}\rightarrow\text{inflation}\rightarrow\text{unemployment}$$

Hope this helps.