Solution: 1, assuming that x students have won the first-class scholarship, then (22-X) students have won the second-class scholarship, and the relationship is 200X+50(22-X)= 1400. So we require x as follows.

200 x+ 1 100-50X = 1400

200x-50x =1400-1100 (shift term)

150X=300

X=2 (person)

Two students won the first-class scholarship.

2. Let the radius of the big circle be r and the radius of the small circle be r,

Ring area: π (r 2; -r^2； ; ) ——————————— area of large circle —— area of small circle, where r is the radius of large circle and r is the radius of small circle.

So according to the area formula of the ring, we can get the relationship: π (r 2-r 2) = 200.

3. 14( 100-r^2)=200

3 14-3. 14r^2=200

3. 14r^2= 1 14

R 2 = 36 (approximately equal to)

R=6 (cm)

A: The radius of the inner ring is about 6 cm.