Determine if the following ratios form a proportion. Also, write the middle terms and extreme terms where the ratios form a proportion:

(a) 25 cm : 1 m = 25 cm : (1 x 100) cm = 25 cm : 100 cm = 25/100 = 1/4 = 1 : 4 

Rs.40 : Rs.160 = 40/160 =1/4 = 1 : 4 

Since the ratios are equal, therefore these are in proportion. 

Middle terms = 1 m, Rs.40 and Extreme terms = 25 cm, Rs.160 

(b) 39 liters : 65 liters = 39/65 =3/5 

6 bottles : 10 bottles = 6/10 = 3/5 = 3 : 5 

Since the ratios are equal, therefore these are in proportion. 

Middle terms = 65 liters, 6 bottles and Extreme terms = 39 liters, 10 bottles 

(c) 2 kg : 80 kg = 2/80  = 1/40  = 1 : 40 

25 g : 625 g = 25/625  = 1/25  = 1 : 25 

Since the ratios are not equal, therefore these are not in proportion. 

(d) 200 ml : 2.5 liters = 200 ml : (25 x 1000) liters = 200 ml : 2500 ml = 200/2500  = 2/25  = 2 : 25 

Rs.4 : Rs.50 = 4/50  = 2/25  = 2 : 25 

Since the ratios are equal, therefore these are in proportion. 

Middle terms = 2.5 liters, Rs.4 and Extreme terms = 200 ml, Rs.50