How is it related to MPC and MPS? 
or
Explain relationship between MPC and multiplier.  

Relationship of K with MPC and MPS. Since multiplier indicates the effects of changes in investment on income via consumption expenditure, therefore K is related to MPC. Greater the MPC (ΔC/ΔY)', greater will be value of multiplier (K). Value of multiplier (K) depends on value of marginal propensity to consume (MPC) and marginal propensity to save (MPS). Symbolically:

(A) There is direct relationship between K and MPC. If MPC is high, K will also be high but if MPC is low, K will also be small as proved below.
(i) Suppose,  then 
(ii) Similarly, if 
   then 
Clearly, value of multiplier has gone up from 4 to 5. Thus K varies directly with value of MPC. Higher the value of MPC, higher will be value of multiplier. Lower the value of MPC, lower will be the value of multiplier (K).
(B) There is inverse relationship between K and MPS, i.e., lower the value of MPS, higher is the value of K- If MPS is high, K will be low but if MPS is low, K will be high. For example, if value of MPS = 3, value of K will be 1/3 as proved in the following example.
(i) Suppose,   then 
(ii) Similarly, if  then