Cost for a family of four to visit 5 popular attractions in Singapore:
Underwater World at Sentosa: S$65.20 (includes admission to Dolphin Lagoon) 
Singapore Zoo: S$50 
Singapore Flyer: S$100.30 
Hippo Open Top Bus: S$72 for one-day Singapore Sightseeing Pass 
National Museum of Singapore: $30 for entry to the museum's permanent exhibitions, giving full-day access to the Singapore History Gallery and Singapore Living Galleries