An observer on sea-coast counts 45 waves in one minute. If the wavelength of the waves is 7 m , then the velocity of the waves will be

Two sources of sound are emitting progressive waves $\mathrm{y}_1=4 \sin 710 \pi \mathrm{t}$ and $\mathrm{y}_2=3 \sin 702 \pi \mathrm{t}$. The sources are placed close to each other. The number of beats heard per second and intensity ratio between waxing and waning are respectively

The closed and open organ pipe have same length and when they are vibrating simultaneously in first overtone produce 3 beats. The length of open pipe is made $\left(\frac{1}{3}\right)^{\mathrm{rd}}$ and that of closed pipe is made 3 times the original, the number of beats produced will be (Neglect end correction)

The length of closed and open pipe is same. The ratio of frequency of $\mathrm{n}^{\text {th }}$ overtone for closed pipe to that of open pipe is (Neglect end correction)