JAMB - Mathematics (1981 - No. 19)
In one and a half hours, the minute hand of a clock rotates through an angle of
90o
180o
640o
450o
540o
Explanation
1 hr, = 60 mins, 60 mins = 360o
30 mins = \(\frac{360^o}{1}\) c \(\frac{30}{60}\)
= 180o
90 mins = 360 + 180o
= 540o
30 mins = \(\frac{360^o}{1}\) c \(\frac{30}{60}\)
= 180o
90 mins = 360 + 180o
= 540o
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